Thanks Fletch. Those are the same islands that we are going to be visiting on our charter this June (with the addition of St. Martin). I doubt my son will be bringing a friend on this one, but you never know.
In any case, we would definitely bring the letter. When I said "not a very big deal" I just meant that it sounds like there aren't any other hoops to jump through, such as unique form requirements for each island.
Matt