Live a board
I am living on a 35 foot Irwin citation in NJ and think it has enough room for 2-4 people. The boat has a separate aft cabin for additional privacy. You should look for a boat with a walk through transom if you are going to scuba dive. I lived on a Hunter 31 for a year but I wouldn''t recommend it for what you are thinking. The beam should be at least 11 feet if you want to not feel cramped. Bargin boats are more costly unless you really are handy and want to deal with all the aggrivation of fixing things that may almost be impossible. Check out past issues of Crusing World as they give you the breakdown on what things really cost on used boats.