Sounds like a neat idea! Only thing is the direct positive paper is what, ISO 3? The 350 and most others have a very slow lens, f/8.8 or so. And the shutter is electronic, how long will it stay open? Normally up to 10 seconds. I can fool my old 100 model into taking a loooooong shot by covering the 'electric eye'. I guess in sunlight we won't need that long an exposure, with sunny sixteen we need 1/3rd second normally, 1/6th with f/8.8 I guess?
Negative paper is also very slow right, about 3 ISO?