This needs a bump. The OP inspired me.
I have some expired 600 film in a Polaroid Sun camera that's not doing anything extraordinary for me. I probably have about five frames left in the camera. I'd like to try exposing some of these in a homemade pinhole camera. Would I be able to remove the pack from my camera (in my darkroom), remove the top frame, expose it in my pinhole camera, replace it in the pack and camera, and then eject it from the camera to develop it (again, all in the dark)? If the first one goes well, maybe I can do the others en masse. Thoughts?
you can do that, it's how I do it.
just remeber to store the pack in a light tight place or if you're going to put it back in the camera before using it again to insert an already exposed frame, so your next unexposed frame doesn't get ejected as the "dark-slide"
another to add.
technique works great if you don't have to roll it yourself.