how to render overlay actors?

I am trying to have an object with a hole that reveals special objects in the world. This is what I have so far using a screen capture actor 2d and hiding/unhiding actor layers every frame then using screen position UV for the material:

However this is not stable when moving the camera particularly in VR. Also the objects in overlay don’t precisely match their true locations:

How is the best approach to improve the stability and object position accuracy?