One problem you'll encounter with plastic reels is that the film "sticks" part way through. It doesn't want to go any further onto the reel.

When this happens, push the reels together gently, toward the film, and rotate gently until it resumes feeding.

The problem is caused by one end of the film catching on a cross-arm of the reel.

I agree with Andy. Do all your loading in a real room if possible. This is much more convenient than a tent or changing bag.
If necessary wait until late night and put black curtains up to close off any stray light.

- Leigh