Maybe check with the Portuguese Embassy or Consulate. Asking this one-of-a-kind question here will get you answers that will make the officials in Portugal
laugh as they impound and confiscate your boat
, or tax/fine/penalize you. The best thing would be to get an official letter with lots of stamps from the Embassy, signed by the ambassador, telling you what the deal is so you can show the people in Portugal and they will have to go along. An email
.... not so much. Of course, things could change after the letter is written, too, making it not worth the paper it's written on. Getting a contact at the Embassy who can keep you up-to-date on changes - and provide a new letter if needed - would be a good idea. Falo Portuguese?