"Texas requires a sales tax to be paid when registering it there but the boat will not be there for many years to come, so that can be delayed."
Don't bet on it. For instance, if you put the home port on the USCG
documentation (please, don't call it registration) papers, they will notify Texas. And if Texas charges use tax, they may come after you for that--even if the boat hasn't entered the state. Or, fifteen years down the line (as happened to a boat owner who "finally" got home to NY) when you do register it they will say "Oh, right, and that's ## years of penalties and interest you owe, you should have paid this when you bought it."
You'll need to check out *all* the possible
taxes and charges that may affect you. Bringing the boat in to the US may require paying a
customs tariff. Bringing it or keeping it in the EU might require VAT. Trinidad? Who knows. If it is US flagged, it may be subject to
import taxes if it is kept more than 90 days (6 months? a year?) in any jurisdiction.
You need to draw up a list of every sovereign that might have a claim on the boat due to any reason (citizenship, residence,
sale, transit, export, import) and then contact each one directly, because these things change from year to year.
And with a UK boat (one sovereign) located in Trinidad (second sovereign) you'd want to make sure there's a good
current title search and there are no claims against the boat. Also beware that Trinidad is one of the few places that allow very effective TBT
bottom paint. But enter US or other waters with that on your boat--and you may have a problem, since most of the world has banned it.