16'+ slips are pretty common on the entire route
...and almost all marinas
charge per length. We have a 14' beam on our gemini catamaran
and have not had any issues where we've sailed (except one marina in Nassau
who wanted to charge us double because we're a catamaran
, even though with our 2' draft
we could fit in the slips that no one else could!). You might have to rig the lines up carefully if there's a large tidal range and no floating piers. Make sure you have a good supply of fenders/boards.