Hedonism in Jamaica allows single men, as does Club Orient in St. Martin. There may well be other resorts that allow singles, I don't know. As far as I know, about the only nude cruises are run by Bare Necessities. I honestly don't know if they allow single men or not. The problem with a cruise or a resort is that usually their prices presuppose two people in a room, and thus you pay more per person if you only have one person in the room.