i personally would never allow a roommate to drive my boat.
Make sure your insurance is up to snuff.... I could see an accident becoming a legal issue reaaaal quickly.
... for what it is worth my buddy and I went to stay in Florida one year for a few months and towed our own boat down... it was about $700 in gas to do this each way.... the next winter we wanted to go back but only for like 6-8 weeks so towing a boat wasn't nearly as practical. Ended up getting a pretty sweet setup at Will Christien's place:
Right on a lake in Winter Haven Florida,
we each had our own rooms,
full access to her boat (X-star) - I had come down to meet her before hand and "proved" I could handle the boat/wasn't a total moron,
with that Said Alan's numbers were pretty close to what we paid, but she was in a nice neighborhood besides the gators (there were some BIG ones in her lake), and the house was fully furnished.