FWIW I asked Chamnoix about reducing backs. It seems to me the combination of a reducing back and one of their other ULF cameras will be a good option instead of the high cost that some rare older cameras command.

I need to draw/cut up some paper to 5.5"x14" to see just how I might like the format. Of course if the "darkroom" didn't have two windows and generally look like a badly organized storage locker I might crop some prints.