GaryL,
Having spent some years in the photoshop business, I'd say the 35mm film that didn't rewind is most likely to be caused from improperly loading the film. Always check the rewind knob (turn counter-clockwise and take up the slack) to make certain it rotates when advancing the film initially. That way, you know if the film has loaded properly on the take-up spool. Now, on the power wind models which I presume you are using, isn't there a take-up knob to check for tension on the film cassette spool? Does your camera pull all the film out onto the take-up spool initally and then pull it back as you take pictures? The motor runs for quite a long time when loading, but just a short time to rewind?
Just another reason why going digital is the way to go for trailcams........I'm not leaving my 35mm camera out there for someone to rip off! As far as flash coverage is concerned, typically modern flash strobes (are very, very small...er punnie is more like it) won't work beyond 12-15 ft. even in bright light! So think about keeping your subject within that limitation since the woods don't reflect anything back to the lens.