Coming from the US a good stopping point would be Isla Mujeres in Mexico. i am not a boater, but I am pretty sure they have a marina where you could stop a day or two and re-fuel.I see plenty of boats in the harbor your size.
here are a few links to websites, and I am sure you can find a site that is more marina-specific.

link:http://www.myislamujeres.com/communicating/open_forum.asp

link:http://www.isla-mujeres.net/home.htm

The first site has a q and a board similar to this one. For more info you could e-mail the owner of JAX, a bar/restaurant advertised on the sites. Jackie is the owner , and her husband operates a deep sea fishing charter out of the marina.