I'm not sure that covers what I want... let me explain in a bit more detail.
I want a completely normal VR setup, except for being able to override a few very specific things. Meaning I want to respect the IPD settings from the HMD, head tracking and positional tracking, etc. Me creating and placing 2 cameras on my own would seemingly go against this.
My main goal isn't to cull differently on each camera/eye.
The difference between what I want and a standard VR setup is that I want to be able to control each camera's transform individually (specifically rotation, position overriding isn't needed in my case).
Essentially, like a chameleon which can look at 2 different places at the same time, 1 place with each eye. Except for the look-at point (or rotation, in my case), which would be non-standard, everything else would follow the normal VR/HMD setup.
As far as I've understood, I can grab the HMD camera nodes in Unity, and potentially tweak them as I want. But since I don't have HMD active, the VR camera mode defaults to None, which makes it impossible for me to test/simulate what I'm trying to do. At least having 2 instances of the Game view active, with each instance set to different eyes lead to identical output, see attached picture. Were it correct, I would expect to see the default offset her and slightly different angles.
https://imgur.com/a/lwp6lNN
EDIT: Halp, can't get the picture to show up properly.