^this. Payload is GVWR-unloaded weight. Period, end of story. You can look stuff up all you want, but the GVWR is printed right on the truck and the cat scales are probably nearby. Fill the tank, load everyone up and all the gear you want in the cab and weigh the truck. Subtract and you will have the one true answer.
Nothing made will absolve you of any liability if you are over GVWR. Helper springs and air bags don't increase GVWR. Can you carry more than the GVWR? Sure, but you do it against the recommendation of the truck manufacture and (potentially) in violation of state law.
Unless Dodge printed the wrong GVWR on your truck, you didn't learn anything. By the way, "payload" as advertised by the manufacturers assumes a base model truck with no options, a 150 pound driver (you weigh only 150 fully clothed?) and an absolutely empty truck. Sometimes they even remove the bumpers before they compute payload.
My truck has a 10,000 pound GVWR. Last time I weighed it with a full tank, the family with coolers, camper shell, some guns and gear etc (I was on a camping trip) it weighed 8,000 pounds on the nose. I had 2,000 pounds of payload left, regardless of what the sales brochure or air bag manufacturer said.
All of that is spot on however you could calculate the actual payload for a given vehicle as it was equipped from the factory instead of using the advertised generic info in sales brochures. There were adjustments that would take into account (for example) the engine and transmission ... diesels are heavier, gas are lighter. They didn't differentiate between trim levels though. The weight difference between a fully equipped leather SLT and a base model was negligible.
Most people are unaware but manual transmissions had a lower CGVWR (and towing capacity) than automatics and by quite a bit.
