I do not know the exact models of the vehicles in question, but I suspect that the 6-8 MPG the spacious motor home gets is considerably lessened by towing an H2 (I believe that is the model of Hummer being towed).
The presence of bicycles and a motorcycle indicate that the tourists in question have at least a passing acquaintance with vehicular gas mileage, but the owners of all these toys clearly are unconcerned with any fanypants notions of saving the planet by going green. In fact, I almost have to admire their brassiness, which comes across like a motorized "f**k you" to any environmentalists they might pass: "Yeah, not only do I drive a big honking RV, but I got a Hummer, too. Wanna take that s**t outside?"