I've moored there several times for the requisite 3 nights and not had any problem with bats. However, I think we were probably closed up for the nights with the generator running and a/c on as there never seems to be any breeze there so probably no way for them to get aboard.
Not an experience I'd like to have. <img src="http://www.traveltalkonline.com/forums/images/graemlins/Yikes.gif" alt="" />