I keep a de-humidifier running over the winter months. It has the facility to drain into the galley sink, but I go on board often enough to empty its 1 gallon container. It works very well even though the boat is otherwise closed up and in a very humid climate.
You could rig a wet and dry vacuum cleaner on a timer plug to suck your bilge dry once a week. But you would have to visit the boat often enough to empty its container. It might reduce the evaporation surface area.