"The Northwest Caribbean". Steve seems to favor the Windward passage route to Guatemala and Honduras. For what its worth, I agree. I have done the trip from PR
, via DR, Haiti, Jamaica, Swan islands to the Bay islands and its a manageable downwind, down current route. I have done the Rio Dulce to Isla Mujeres trip North and its was OK. I would NEVER do it the other way on a sailboat. You are sailing a lee shore and bucking 2kts + Gulf stream until you hit the Belize border. I met one boat that ended on the reef and heard of a number of others. The trip from Florida to Isla can be less that fun as well.
This is one case where the much longer route is preferable. I am frequently amazed why people think that staying close to shore is intrinsically safer that being offshore.
Two other points (not that you asked). You say that you have a cheap boat and then you insured it??. Why not put the insurance money into a slightly better boat OR improved rigging or ground tackle?
Check out riodulcechisme.com, its a Rio board but covers the Bay islands. I would investigate the possibility of sailing as unpaid crew on a larger sailboat and gaining experience that way. I am reasonably sure you could get cheapish accommodation in the Bay islands or even house or boat sit.