Consider the person with a truck, 11' slide-in camper and towing a cargo trailer. Here you have the opportunity to match up all 3, the GVWR, the rear axle GAWR, and the combo GCWR. All that is within specifications, and roads, hills, stopping, starting, bouncing - all that is lumped in to the vehicle's brakes, drive line and suspension design. There is no practical difference between that setup and towing a 5th wheel that produces the same GCWR and GAWR characteristics, except, I believe most would agree, the 5th wheel tow is safer. GVWR rating is for the vehicle and the contents it has to stop and start. GAWR is the rated capacity of axle, tires and rims. If a load is directly over the axle and the load has it's own brakes, it's the GAWR that controls. In general, if you tow a brake equipped vehicle, governing capacities are the GCWR and each of the GAWRs. For many vehicles, but not all, the GVWR is the sum of the two GAWRs. I just hate to see someone trade trucks only because his/her 5th wheel puts the truck and pin box weight over the GVWR when the axle GAWRs are good, brakes are good, and towed combo GCWR is good.