The mod idea sounds good, I’ll explore how much effort that would take.
The workaround I described above works well though for most portals and for the ones where the glitch makes the game too difficult you can temporarily disable DirectVR:
you can deal with the matter by releasing the forward button whenever you enter a portal. That way you come to a halt on the other side and can reorient if necessary. Works well for the vast majority of portals, except one or the other situation towards the end, where you might want to disable DirectVR temporarily (ALT+B per default).