Campfire, just to set the record straight -- I have a tiny trailer pulled by a moderate truck (a Tacoma), and (as we expected) we get bad mileage, just like everyone else, due to the wind resistance. So no one should get a small trailer to save on gas, except a pop-up (which has less wind resistance). We got a small trailer because we like to go into very remote places. But not everyone would find the tight quarters to be comfortable.
On the plus side, it takes almost no time to wash -- and I can dry the whole thing with a handkerchief!