When you talk to the car rental place, ask if they'll meet you at the ferry, or at your place on Lambert Beach. I forget the name of the place we used in November (might be able to find out if you need it), but they came to the TMM base to give me the car, and then told me what he wanted me to do with the keys so we could drive ourselves to the ferry and left the car there for him to pick up, and saved ourselves a taxi ride. Did the same thing a couple of years back when I needed a car for a couple of days. Incredibly handy, but you have to ask!

Good luck and have fun!