If you want to save gas, and can stand being cramped into something small, the Ford Transit Connect would work. You could tow a very small pop-up camper (like the ones small enough to be towed by a motorcycle) for one or two people, and the other two can sleep inside the Transit Connect. Otherwise, you should be looking at regular full-sized vans, of which I like both the Ford and Chevy varieties. Try to stay away from the Mercedes/Freightliner/Dodge Sprinter. As a diesel, it has a high sticker price, and with a Mercedes engine, repairs are frequent and expensive.