I went through a phase looking at many medium duty dualcab utes like Toyota Hilux as an example. The payloads are quite small usually just under 1000kg on kerb weight, then take the weight of a decent aftermarket tray & your payload is no better than a family wagon. I was turned off by all the reports of bent chassis, but confused as there are GVM upgrades that seem to magically allow you to carry alot of extra weight. But they don’t seem to do anything to the chassis directly itself.
So are these GVM upgrades just a legal thing that only applies to the smooth asphalt roads?
AFAIK these upgrades usually apply to suspension and brakes. Hard to see how they would affect chassis strength - manufacturers do not generally allow much margin for safety.
I suspect an upgrade might deal more the braking and handling aspects rather than the cars durability.
Most bent chassis seem to be the result of aftermarket airbags or incorrect loading. Ideally a fair proportion of your load should be in the rear of the cab and not too much behind the rear axle, if you can spread the load correctly a GVM upgrade might be in order.