I know these things aren't exactly fuel efficient or bought for that purpose but what sort of mileage are you guys getting with the camper on and is your rig gas or diesel?
Running a Ford 6.0 diesel in a an F250, short bed,crew cab,4X4,and carrying a Lance 825, about 2K pounds. I get 12MPG,running 70 to 80 MPH on the highway after 230 miles.