One thing I always did in addition to what others have already said, is leave something in the boat that if all else fails they want to create their nest with. Something they can chew on that isn’t part of your boat. I always used small scraps of pine and a roll of toilet paper or paper towels.
In the spring sometimes I found that they had built a nest on the floor with the paper towels, ate the poison and died in the paper towel nest.