diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9e5bb76f..3739fd76 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,7 +12,7 @@ Changelog for Cass Operator, new PRs should update the `main / unreleased` secti
 ## unreleased
 
 * [FEATURE] [#651](https://github.com/k8ssandra/cass-operator/issues/651) Add tsreload task for DSE deployments and ability to check if sync operation is available on the mgmt-api side
-* [FEATURE] [#701](https://github.com/k8ssandra/cass-operator/issues/701) If ReadOnlyRootFilesystem is set, always use the new config builder instead of the old one. This change only applies to Cassandra 3.11, 4.0 and DSE 6.8, 6.9. Note that not all the versions mentioned here necessarily support ReadOnlyRootFilesystem. 
+* [FEATURE] [#701](https://github.com/k8ssandra/cass-operator/issues/701) Allow ReadOnlyRootFilesystem for DSE also with extra mounts to provide support for cass-config-builder setups
 
 ## v1.22.2
 
diff --git a/pkg/reconciliation/construct_podtemplatespec_test.go b/pkg/reconciliation/construct_podtemplatespec_test.go
index 98db5f8a..7335d675 100644
--- a/pkg/reconciliation/construct_podtemplatespec_test.go
+++ b/pkg/reconciliation/construct_podtemplatespec_test.go
@@ -1970,8 +1970,38 @@ func TestReadOnlyRootFilesystemVolumeChanges(t *testing.T) {
 	podTemplateSpec, err := buildPodTemplateSpec(dc, dc.Spec.Racks[0], false)
 	assert.NoError(err, "failed to build PodTemplateSpec")
 
+	initContainers := podTemplateSpec.Spec.InitContainers
+	assert.NotNil(initContainers, "No init containers were found")
+	assert.NoError(err, "Unexpected error encountered")
+
+	assert.Len(initContainers, 2, "Unexpected number of init containers returned")
+	assert.Equal(ServerBaseConfigContainerName, initContainers[0].Name)
+	assert.Equal(ServerConfigContainerName, initContainers[1].Name)
+
+	assert.True(reflect.DeepEqual(initContainers[0].VolumeMounts,
+		[]corev1.VolumeMount{
+			{
+				Name:      "server-config-base",
+				MountPath: "/cassandra-base-config",
+			},
+		}), fmt.Sprintf("Unexpected volume mounts for the base config container: %v", initContainers[0].VolumeMounts))
+
+	assert.Equal(initContainers[0].Args[1], "cp -rf /etc/cassandra/* /cassandra-base-config/")
+
+	assert.True(reflect.DeepEqual(initContainers[1].VolumeMounts,
+		[]corev1.VolumeMount{
+			{
+				Name:      "server-config",
+				MountPath: "/config",
+			},
+			{
+				Name:      "server-config-base",
+				MountPath: "/cassandra-base-config",
+			},
+		}), fmt.Sprintf("Unexpected volume mounts for the base config container: %v", initContainers[0].VolumeMounts))
+
 	containers := podTemplateSpec.Spec.Containers
-	assert.NotNil(containers, "Unexpected containers containers received")
+	assert.NotNil(containers, "No containers were found")
 	assert.NoError(err, "Unexpected error encountered")
 
 	assert.Len(containers, 2, "Unexpected number of containers containers returned")
@@ -2026,8 +2056,38 @@ func TestReadOnlyRootFilesystemVolumeChangesHCD(t *testing.T) {
 	podTemplateSpec, err := buildPodTemplateSpec(dc, dc.Spec.Racks[0], false)
 	assert.NoError(err, "failed to build PodTemplateSpec")
 
+	initContainers := podTemplateSpec.Spec.InitContainers
+	assert.NotNil(initContainers, "No init containers were found")
+	assert.NoError(err, "Unexpected error encountered")
+
+	assert.Len(initContainers, 2, "Unexpected number of init containers returned")
+	assert.Equal(ServerBaseConfigContainerName, initContainers[0].Name)
+	assert.Equal(ServerConfigContainerName, initContainers[1].Name)
+
+	assert.True(reflect.DeepEqual(initContainers[0].VolumeMounts,
+		[]corev1.VolumeMount{
+			{
+				Name:      "server-config-base",
+				MountPath: "/cassandra-base-config",
+			},
+		}), fmt.Sprintf("Unexpected volume mounts for the base config container: %v", initContainers[0].VolumeMounts))
+
+	assert.Equal(initContainers[0].Args[1], "cp -rf /opt/hcd/resources/cassandra/conf/* /cassandra-base-config/")
+
+	assert.True(reflect.DeepEqual(initContainers[1].VolumeMounts,
+		[]corev1.VolumeMount{
+			{
+				Name:      "server-config",
+				MountPath: "/config",
+			},
+			{
+				Name:      "server-config-base",
+				MountPath: "/cassandra-base-config",
+			},
+		}), fmt.Sprintf("Unexpected volume mounts for the base config container: %v", initContainers[0].VolumeMounts))
+
 	containers := podTemplateSpec.Spec.Containers
-	assert.NotNil(containers, "Unexpected containers containers received")
+	assert.NotNil(containers, "No containers were found")
 	assert.NoError(err, "Unexpected error encountered")
 
 	assert.Len(containers, 2, "Unexpected number of containers containers returned")
@@ -2058,7 +2118,186 @@ func TestReadOnlyRootFilesystemVolumeChangesHCD(t *testing.T) {
 			},
 		}), fmt.Sprintf("Unexpected volume mounts for the cassandra container: %v", containers[0].VolumeMounts))
 
-	// TODO Verify MCAC is disabled since it will fail with ReadOnlyRootFilesystem
+	mcacDisabled := corev1.EnvVar{Name: "MGMT_API_DISABLE_MCAC", Value: "true"}
+	assert.True(envVarsContains(containers[0].Env, mcacDisabled))
+}
+
+func TestReadOnlyRootFilesystemVolumeChangesDSE(t *testing.T) {
+	assert := assert.New(t)
+	dc := &api.CassandraDatacenter{
+		Spec: api.CassandraDatacenterSpec{
+			ClusterName:            "bob",
+			ServerType:             "dse",
+			ServerVersion:          "6.9.2",
+			ReadOnlyRootFilesystem: ptr.To[bool](true),
+			Racks: []api.Rack{
+				{
+					Name: "r1",
+				},
+			},
+		},
+	}
+
+	podTemplateSpec, err := buildPodTemplateSpec(dc, dc.Spec.Racks[0], false)
+	assert.NoError(err, "failed to build PodTemplateSpec")
+
+	initContainers := podTemplateSpec.Spec.InitContainers
+	assert.NotNil(initContainers, "No init containers were found")
+	assert.NoError(err, "Unexpected error encountered")
+
+	assert.Len(initContainers, 1, "Unexpected number of init containers returned")
+	assert.Equal(ServerConfigContainerName, initContainers[0].Name)
+
+	assert.True(reflect.DeepEqual(initContainers[0].VolumeMounts,
+		[]corev1.VolumeMount{
+			{
+				Name:      "server-config",
+				MountPath: "/config",
+			},
+		}), fmt.Sprintf("Unexpected volume mounts for the base config container: %v", initContainers[0].VolumeMounts))
+
+	containers := podTemplateSpec.Spec.Containers
+	assert.NotNil(containers, "No containers were found")
+	assert.NoError(err, "Unexpected error encountered")
+
+	assert.Len(containers, 2, "Unexpected number of containers containers returned")
+	assert.Equal("cassandra", containers[0].Name)
+	assert.Equal(ptr.To[bool](true), containers[0].SecurityContext.ReadOnlyRootFilesystem)
+
+	assert.True(reflect.DeepEqual(containers[0].VolumeMounts,
+		[]corev1.VolumeMount{
+			{
+				Name:      "tmp",
+				MountPath: "/tmp",
+			},
+			{
+				Name:      "etc-cassandra",
+				MountPath: "/opt/dse/resources/cassandra/conf",
+			},
+			{
+				Name:      "dse-conf",
+				MountPath: "/opt/dse/resources/dse/conf",
+			},
+			{
+				Name:      "spark-conf",
+				MountPath: "/opt/dse/resources/spark/conf",
+			},
+			{
+				Name:      "collectd-conf",
+				MountPath: "/opt/dse/resources/dse/collectd/etc/collectd",
+			},
+			{
+				Name:      "server-logs",
+				MountPath: "/var/log/cassandra",
+			},
+			{
+				Name:      "server-data",
+				MountPath: "/var/lib/cassandra",
+			},
+			{
+				Name:      "server-config",
+				MountPath: "/config",
+			},
+		}), fmt.Sprintf("Unexpected volume mounts for the cassandra container: %v", containers[0].VolumeMounts))
+
+	// Test that cassandra-base-config isn't here
+
+	mcacDisabled := corev1.EnvVar{Name: "MGMT_API_DISABLE_MCAC", Value: "true"}
+	assert.True(envVarsContains(containers[0].Env, mcacDisabled))
+}
+
+func TestReadOnlyRootFilesystemVolumeChangesDSEWithClient(t *testing.T) {
+	assert := assert.New(t)
+	dc := &api.CassandraDatacenter{
+		ObjectMeta: metav1.ObjectMeta{
+			Annotations: map[string]string{
+				api.UseClientBuilderAnnotation: "true",
+			},
+		},
+		Spec: api.CassandraDatacenterSpec{
+			ClusterName:            "bob",
+			ServerType:             "dse",
+			ServerVersion:          "6.9.2",
+			ReadOnlyRootFilesystem: ptr.To[bool](true),
+			Racks: []api.Rack{
+				{
+					Name: "r1",
+				},
+			},
+		},
+	}
+
+	podTemplateSpec, err := buildPodTemplateSpec(dc, dc.Spec.Racks[0], false)
+	assert.NoError(err, "failed to build PodTemplateSpec")
+
+	initContainers := podTemplateSpec.Spec.InitContainers
+	assert.NotNil(initContainers, "No init containers were found")
+	assert.NoError(err, "Unexpected error encountered")
+
+	assert.Len(initContainers, 2, "Unexpected number of init containers returned")
+	assert.Equal(ServerBaseConfigContainerName, initContainers[0].Name)
+	assert.Equal(ServerConfigContainerName, initContainers[1].Name)
+
+	assert.True(reflect.DeepEqual(initContainers[0].VolumeMounts,
+		[]corev1.VolumeMount{
+			{
+				Name:      "server-config-base",
+				MountPath: "/cassandra-base-config",
+			},
+		}), fmt.Sprintf("Unexpected volume mounts for the base config container: %v", initContainers[0].VolumeMounts))
+
+	assert.Equal(initContainers[0].Args[1], "cp -rf /opt/dse/resources/cassandra/conf/* /cassandra-base-config/")
+
+	assert.True(reflect.DeepEqual(initContainers[1].VolumeMounts,
+		[]corev1.VolumeMount{
+			{
+				Name:      "server-config",
+				MountPath: "/config",
+			},
+			{
+				Name:      "server-config-base",
+				MountPath: "/cassandra-base-config",
+			},
+		}), fmt.Sprintf("Unexpected volume mounts for the base config container: %v", initContainers[0].VolumeMounts))
+
+	containers := podTemplateSpec.Spec.Containers
+	assert.NotNil(containers, "No containers were found")
+	assert.NoError(err, "Unexpected error encountered")
+
+	assert.Len(containers, 2, "Unexpected number of containers containers returned")
+	assert.Equal("cassandra", containers[0].Name)
+	assert.Equal(ptr.To[bool](true), containers[0].SecurityContext.ReadOnlyRootFilesystem)
+
+	assert.True(reflect.DeepEqual(containers[0].VolumeMounts,
+		[]corev1.VolumeMount{
+			{
+				Name:      "tmp",
+				MountPath: "/tmp",
+			},
+			{
+				Name:      "etc-cassandra",
+				MountPath: "/opt/dse/resources/cassandra/conf",
+			},
+			{
+				Name:      "dse-conf",
+				MountPath: "/opt/dse/resources/dse/conf",
+			},
+			{
+				Name:      "server-logs",
+				MountPath: "/var/log/cassandra",
+			},
+			{
+				Name:      "server-data",
+				MountPath: "/var/lib/cassandra",
+			},
+			{
+				Name:      "server-config",
+				MountPath: "/config",
+			},
+		}), fmt.Sprintf("Unexpected volume mounts for the cassandra container: %v", containers[0].VolumeMounts))
+
+	// Test that cassandra-base-config isn't here
+
 	mcacDisabled := corev1.EnvVar{Name: "MGMT_API_DISABLE_MCAC", Value: "true"}
 	assert.True(envVarsContains(containers[0].Env, mcacDisabled))
 }