We did work on a large format project that unfortunately never came too, that was back in the early 90's and it involved using using a 58mm Scheider and a Linfhof roll film back of 6cmx12cm.
Hurdles I remember that we faced:
Film sheet was not considered due to the necessity to remove and reinsert the dark slide for every exposure, instead a roll film back of the Graflock type was used that at least gave the shooter a few exposures for bracketing (six if I remember well)
Focusing, it was considered to use the Nikonos approach but sticking to preset distances would most likely have been the more pratical approach. this was projected to be done by using spacers to move the lens to a specific distance to match the virtual image projected by the dome.
Advancing the film was fairly straight forward since the roll film back had a lever similar to the 35mm film camera. more complex was linking the aperture and shutter speed on these view camera lenses and the arming of the shutter mechanism, triggering on the other was child play by using a plunger type of cable release.
This was to be a one lens, one size of film camera destined to do large billboard for a French resort consortium. Coming from a large format background myself, I can tell you that you should shut down any dreams of using sheet film underwater, if any thing I would probably consider working around a Linhoff or Fuji Panoramic camera with something like a 6x17cm format, keep the roll fim back and the lens and have an aluminum body machined that can accept off the shelf dome port of 8" or wider with a latched rear door that will give access to the roll film back.
shutter speed can be accessed via a pinion gear mechanism (the ring has notches that closely resemble gear teeth, the itch is the aperture IMO, the pesky lever is normaly very small and oddly located under the lens, the arming of the shutter should be no major hurdle.
Hope you have some good ressource if you want to tackle this baby, it sure is not a weekend project 
If Louis Boutan could do large format underwater photograph all the way back in 1893, I'm sure it can be done today, but is it worth it?