Need help finding my mom waterproof fishing boots.

We're going to Alaska in August and mom's the only one who hasn't found waterproof fishing boots yet. Need advice on the subject.

We'll be on a boat for most of the fishing, so obviously something good for that. Mom's handicapped after having major back surgery and doesn't walk or stand for long. Anything that can help her keep her grip on board. But they also have to be lightweight as she has trouble lifting her legs and so far all of the fishing boots we've tried are too heavy for her. She wears a 5 1/2 Extra Wide and has large calves so likely it'll have to be something ankle high as anything higher than that and she won't be able to get it on. Plus her legs and feet tend to swell.

If someone knows good brands to look into to see if we can find them in nearby stores for her to try on, I'd appreciate it. It's really hard to find good shoes when one has small but wide feet and the only wide width shoe store we know does not sell any sort of fishing or hiking shoes for women.