it' me again. coming back to the initial questions of this thread: I have a super 23 with the G (graflex) mount. with some smaller modifications I could attach a horseman polaroid back which is kind of G mount. the film plane of the horseman back is about 10mm further to the back, that's why they furnish a spacer for focussing. if you attach the collapsible 100mm lens and you collapse it, it moves about 10mm to the back. so you can focus with the finder. but there is no room for movements of the back, which was my aim. no focussing to infinity possible with all the other lenses. so this was a nearly useless (and quite expensive) experiment.

perhaps I'll try to hack an M type roll film back and fix it to a polariod back which seems possible to me. I'll come back to this if I succeed.