I just arrived in Antigua, I'm in Falmouth Harbour. If you don't get an answer here, I'll be meeting my local friends tonight and one of them runs a commercial fishing boat here and should be able to give a qualified answer. I know that the charter fishing boats (the big go-fast ones) go further than 10 miles out in order to get to the drop-off and they certainly don't clear in and out each time. But their commercial licensing might give them an exception, if such a law/rule actually exists.