Looking at the source for 4.6, there’s a console variable to disable CustomDepth which might be helpful for your purpose:
static TAutoConsoleVariable<int32> CVarCustomDepth(
TEXT("**r.CustomDepth**"),
1,
TEXT("0: feature is disabled
")
TEXT("1: feature is enabled, texture is created on demand
")
TEXT("2: feature is enabled, texture is not released until required (should be the project setting if the feature should not stall)"),
ECVF_RenderThreadSafe
);