Ther is another opeion than just a B.
There are poptop slide-in truck campers -I believe both Lance and Skamper make a model and may others as well.. I saw one at Caballo State Park in NM where some Canadians parked close to us were traveling the southwest and wintering in it. A little small for us, but -30 in Canada can make small and 65 in southern NM seem real big! ;D You'd have to get a truck, but with a diesel for mpg I think you might be in the ballpark height wise. And you could back-country boodock a lot easier.