Based on the comments i build the setup myself, created the "P" face as it was called in place, took it down flat according to comments again and then started working it back in place.
Here a visual step by step:
It's based on the following:
Begin by creating a support triangle.
For that use K knife tool and hold Ctrl to snap on the middle of the base ...
If you use the 'Mist' feature:
then enable it in the camera settings:
then adjust the start and end point that it gives you to the start and end of the model, in the world settings:
And finally, in the compositing editor, connect the mist pass to the render pass, to give you a high definition 'depth' pass:
Hope this helped!
As far as I know you can't modify the default setting easily but you can use a simple node group to force the behaviour wherever you want to use your image texture node :
Related : https://blender.stackexchange.com/a/168033/86891
Please refer to piegames answer. PNG is perfectly fine for a "transport" data format. You can even use PNG and push a full 32bit raw into each pixel, then in your shader or depth system unpack the RGB/A into the original depth value.
Im not sure why @user1853 is pushing EXR, this is not used very heavily for depth maps in my experience. EXR is not a great ...