So why don't you buy the boat in Florida, sail around the Carib for a few years then take it to your home waters? I understand there is no sales tax in Florida (smart move on their part) and annunal registration can't be more than a few hundred dollars a year. Carib moorings shouldn't be more expensive than Med moorings and travel will probably be a wash.
Also, does paying the VAT immediately upon entry in Eurozone apply to USCG documented vessels?
Also, buy it without sails and equipment to establish purchase basis then add all the toys later at six to eight percent sales tax or over the internet and no sales tax.
I'm not a tax lawyer, or lawyer of any type and my advice might get you in trouble with the tax man, but if you really love that boat then there must be some way to defer the VAT.
Go talk to a tax man.
I've enjoyed this thread immensly, thanks.