MFG GVWR is for warranty issues, CLASS designations and registration fees.
Payload is based on the MFGs GVWR
Mfg. GVWR has no legal standing per se. ---Many states allow registration higher then MFG GVWR so States don't even recognize it as a concern
Axle & Tire Max Load Ratings ARE legal statutes
Do NOT exceed those ratings.
Load up truck camp ready.fuel passengers stuff in cab and then go to CAT Scales and get weighed
Front Axle, Rear Axle and Total weight.
How much weight can you add to axles & tire loads w/o exceeding them?
Now you have real numbers to work with.
Truck Campers.....look at their GVWR.
Got enough axle/tire load to handle that weight?