The Yashica camera in question is not what I call 'fun'. But hey, horses for courses. The sensor could slide in and out, as mwmcbroom suggested - which would add to the cost of the module. You could also make different modules for different cameras. Or, as John Robison said, you could have a relatively compact back, possibly with a short base extension. As for resetting and activating the sensor module, medium format cameras used a PC cable. I think a similar arrangement would work with 35mm cameras. Most 35mm cameras have first-curtain sync by default - not great for flash photos but great for triggering a digital sensor.