All you need to do is cut them off at the water line. With a chain saw and a stable platform that wouldn't be too difficult unless you have a lot of trees. Above water trees don't provide any fish structure anyway.
That won't completely rid you of the problem but it will help. At least they won't use you as a Motel 6 that way. Once they find you, and they do have their ways, they will return. You just have to make sure they know they aren't welcome at all/any times.
