Golf cart is OK. We used one from El Pescador Villas a few times. It takes longer than by boat, of course, the "roads" being what they are North of the cut. Timing things to use the Island Ferry is not so bad as it seems. Water taxi will cost more than the Ferry, of course, but then, it's right when you want it, pretty much.
Count on 12 minutes to town from where you are by boat, maybe 25 by golfcart.
We never had long lines at the ferry, either. (February)