If the intruder was injured or a body turned up they would be looking for the other party (you) ASAP and sailboats aren't good for a fast get-away. If they found you, you would be detained in jail (probably for a long time even if eventually found innocent of all charges) and much if not all of your remaining funds would be expended trying to obtain your get out of jail card.

As to your contention that "most third world countries that have gun control probable wouldn't have a law that dealt with modified ammunition anyway and flare guns are legal"... Do you really think some technicality or loophole would save you in a third-world legal system if they ban guns?