Sorry to revive an older thread, but I have a couple questions for Kav. What time interval are you going to use, and just exactly how unattended does the camera need to be? I was thinking that a Hasselblad A32 back might work for you - certainly you can still get some color films in 220-size and getting them processed should not be a problem. You'll only get 32 shots instead of 100, but that's still a fairly large number of shots in one magazine. If your situation would let you reload periodically, might this work?
The interval would depend on how many shots I can take with out reloading, I have a back for 120 & 220 film. I will look into the A32 back. Otherwise I will just use what I have on hand. I would only be able to shoot one roll of film a day for this project. Thanks for the info!