One trick for cheating exposures would be to load your camera in complete darkness, and shoot onto the area that you normally use to prime the takeup mechanism of your camera.
Another would be to use an old Leica. The frames are dangerously close on them (I would take off a sliver of a frame from time to time when cutting the negs), and I always got at least 38 frames from my IIIc and IIIa. 39 was not uncommon, and 40 was not unheard of.
I only heard Leica, Nikon, and Olympus mentioned for the 250 shot backs. There is a Canon F-1 version as well, which I have along with the loader, the interval timer, and the motor drive, and all original boxes and instructions. It all came together. It was quite a find. Obviously never once used. Each 250 shot cartridge uses about 1/3 of a 100 foot bulk roll. But how to develop the stuff without a slice through every 36th frame?

Roller transport is the only way, I guess.