olle,
what you are saying sounds legit now that I think about it.
Rise, fall & shift will definitely tax image circle but simple tilt probably doesn't but I'm not 100% sure.
Maybe someone knows ?

I'm not even sure how large the pola back image produces but I have seen in the mamiya literature that only certain lenses wll cover so it must be larger than 6x9.

I only have a regular 6x7 back for my Super 23 but can shoot an image and upload to flickr or somewhere.