As for swim diapers — I would probably do an iPlay one that is re-usable, as they truly do hold poop accidents in the pool (per my experience, anyway). (godiaperfree.com)
She has had a few poop accidents, but ZERO pee accidents! (thegarciadiaries.com)
It's up to you to prevent pee and poop accidents rather than allow them to happen even once because each time the puppy empties bladder or bowel inside, it slows the housebreaking process. (thedogplace.org)