It's a real no-no. In every island nation that I know of in the Caribbean
, if you stop for any reason -- no matter how short the stop -- the law requires you to check in. These are mostly (by U.S. standards) fairly poor countries, so the fees
that they collect are important to them. As such, they are not much inclined to look the other way when people they perceive as "rich yachtsmen" violate their laws.
(I know, I know. You're not rich. Lots of cruisers aren't, really. Not by our standards. But that's the perception that exists, so you have to live with it.)