The most extreme example would be a Power Wagon. Its axles, drivetrain, brakes, frames, is functionally identical to a 3500 dually. The only limiting factor is the suspension. In that case I won't blink an eye going over GVWR once the springs are upgraded, up to whatever a SRW 3500 is rated at.
Real world example here… our 18 PW fully loaded up to return home to AK after a year of living in the lower48. Kept heavy items centered and low as I could, but was still full up in backseat and bed/canopy. Got curious after filling up at a truck stop in Canada and ran across the scales.
Drove fine. Stopped fine. But it was also 3500mi of highway, mostly in the 60-65mph range and I knew I was heavy so I drove like it. Even in the northern Canadian Rockies, the twists of the mountain roads weren’t bad. The frost heaves were another horrific story so I tried not to drive at night so I could see them ahead of time. Overheating also inconclusive since it was -20 to -40 the whole time.
Long story short… I’m an open critic of the PW payload limitation, but also love the truck for everything else. Would I load to 900lbs above payload for a backcountry trip or US highway (80mph) trip? Probably not. Would I do it every day as a matter of course? Absolutely not. But I’m sure that our regular load for a big camping trip puts us right at or slightly above. I don’t cross axle limits nor tire limits, and try to keep sticker most of the time.
