Try this out:
Anything beyond the DistanceToBlendOut will use the SceneTexture:PostProcessInput0 (which is the scene color with post processing). This will apply to everything not added to custom depth because anything that isn’t set to render in it will be treated like it is the max distance away.
If you want things not RCD to render normally in front of things set to RCD then you need one more check to compare the actual Scene Depth versus the Custom Depth:
So here is a comparison of each step:
