I was thinking about doing something similar with an old Polaroid roll film camera. Just clip down some film to fit as single shots. I didn't end up doing it because the lens has some issues. I did do it with my 116 Voightlander pinhole conversion. I cut down a 4x5 sheet about 1/2 inch in one direction and placed it in the camera. I used a cheap little plastic cutting table with a stop to cut the film to the proper length. I had to block out the cameras frame counter window to make it work. I would think your method would work with pack film and integral film, as long as you can keep the integral camera from spitting out the negative.
