Your citizenship/working area combos are not something I'm familiar with. From what I understand (and this is from a limited experience... it may not be fact): If you crew on a vessel flagged from your native country, you can crew anywhere in the world. You need no working papers because you are not working for any business in the country you are "visiting" aboard the vessel that employs you.
This is how it worked for me when I was crewing
. I worked for a US flagged boat, and went through customs
as paid crew on that boat. No extra paperwork required, since I was a US citizen working on a US vessel. If you can work on a boat flying the Union Jack, you'll be in good shape. A large number of boats in the Caribbean
fly that flag.