I probably wasn't too clear earlier, when I said it [aeration via O2] might not help too much. I meant this: if bleach already has enough aeration, then more won't help. The C-41 process seems to have a pretty good margin for error, that's why I asked my previous questions.
Your plan to shake a small amount of bleach in a large bottle is an easy way to get some aeration. I suspect that just pouring it in and out of your tank, or whatever, is already enough.