I'm looking to live in some kind of vehicle as a long term thing. What should I get?

I live with my parents now but I'll probably be 20 or 21 when I do this and I plan to live in the vehicle for... at least 3 years I figure. What is the cheapest thing I can possibly get? Including insurance and fuel consumption and everything. I don't even need a bed (I'm comfortable on the floor). Just a refrigerator, freezer, stove, and toilet would be nice too. I'm going to buy used of course. Should I get a work van and put that stuff in it? Or a camper van or caravan? (Though those usually have a bunch of stupid unnecessary junk like tables and couches)