Of a Truck/Camper(that with kitchen/bath) combo with high MPGs. Now, I'm assuming it's going to be diesel, but I'm also curious what one can get on the half-ton campers.
We got relatively good mileage on our 6,000+ mile tour of the Pacific Northwest: between 14 mpg (at 65 to 70 MPH) and 17 mpg (60 mph) with our 2014 Ram Hemi 1500. But my popup camper doesn't have a bath or holding tanks, so it has a lower profile and less weight than what the OP hopes to find.