Well, I *think* you can do it this way: I took two 120 spools, cut em in half and then welded them together such that there is the right distance to feed 5" roll film on there. I think 5" sheet would work. I haven't tried it as yet but I suspect that it'd work.
So far I am just tray dev'ing 5x7. I also have some dip tanks but haven't tried them.
I can see what I did with my contraption and maybe I can give it a go and report. My recollection was that I found 5" aerial rollfilm to be too flimsy to work with my contraption, but ordinary 5x7 might be just fine. It needs some rigidity or it buckles out.
Apart from that, sure, there are inserts for tubes and you can do all the sheet sizes that way, in daylight.