Many thanks everyone. My plan is to build a "box" that would mount behind the lensboard, inside the bellows behind the front standard. I'm not worried about lost infinity-focusing using this method, since this is a 12x20 it is going into, and the shortest lens I'll ever have on the camera is probably a 450 Apo-Nikkor M.
This has given me some really good ideas - I'll just have to hit a good hobby shop - question remains if such a place exists around here anymore. I remember growing up in a small town and we had a really big one downtown, on main street. Uptown Sales, it was called, and they had four floors of hobby supplies. Everything from model cars, planes, tanks and boats to balsawood, model rockets, paints, glue, chemistry sets, the works. I don't think they're in business anymore though. I haven't been back to the town I grew up in for ages.