new NHTSA regs 571.120 as of 6/15/08 says the trailers GAWR must match the trailers GVWR plus the hitch weight. Prior to that date RV manufactures were installing axles that equaled GVWR minus the trailer hitch weight.
TX DOT (commercial) got me on a 36' GN flatdeck/3500 DRW Chevy towing with a 29k GCW plates. The GN had no GVWR tag. TX DOT went under the trailer and got the axle rating. Luckily all three axle had tags. They could have put me in the impound lane but the DOT guy was nice and said to have the mfg send me a GVWR tag. These guys see this all the time as he even gave me the trailer mfg 1-800 number.