No comment on US regulations, the AAA guide looks like a good source of info.
I agree with other posters that tire and axle ratings matter more than GVWR.
But that said, there are jurisdictions where GVWR matters and is enforced. In British Columbia, due to road safety concerns, RV GVWRs became a focus. BC regulations may matter to some posters, given interest in the Alaska Highway, which starts in BC.
Note that tow ratings aren't regulated here, but GVWR and GAWR are. Enforcement is carried out by the Commercial Vehicle Safety Enforcement group within the provincial Ministry of Transportation, and applies to privately owned RVs, whether they are registered in BC or not. Testing is usually done with portable scales at safety check points, keeping the commercial scales clear for trucks.
Spot checks are done based on visual clues, including trucks not appearing to be level.
Info sheets for reference:
http://www.cvse.ca/vehicle_inspections/PDF/MV3230.pdf
http://www.cvse.ca/references_public...82003)GVWR.pdf
Jeff