It always helps to see things in practice. You can easily keep fillets you bagged in the morning and have them for dinner. I have no qualms about 24 hours with day time temps at 89 and night time at 69. They don't quiver when you bread 'em but they still smell and taste fine.

I do bring along a little bottle of bleach for the gauzy towel I wrap fish and/or filtered water in and my water bottle cozy. After a few days they get that sour dish rag odor so I boil/bleach whatever bacteria that causes that smell away every few nights.

Cleaning fish in camp was never a good idea anyway - even when there were enough gulls waiting... and fish never did portage well hanging from a stringer.