Hey HellGate,
We first would like to apologize on our delay in providing you a fix.
On our latest build we added a new input port to both Surface Depth and Camera Depth Fade so you can place a custom vertex position and it will do its calculation according to that instead of the current vertex position.
You can download it over here:
https://amplify.pt/download/
So, to use Screen Depth with a custom vertex offset you can do something like this:

- CustomVertexOffsetDepth.jpg (145.7 KiB) Viewed 3816 times
Please notice that we changed the Vertex Output option on the Node Properties from Relative to Absolute as we are specifying a final vertex position and not an offset.
Please don't hesitate on reaching us if you stumble into any issues.