We were truck camper people back in the late '60s/'70s and early '80s. During that period we had three different TCs (8' and a 9' 6" and a 10' 6") on various trucks.
I never did a thing to them till I loaded it all up, made a short trip, and then made a decision if any type mod (suspension...drivetrain/etc was needed. Now having hauled commercially I never carried weight above any of my trucks GAWRs especially RAWR as its carried all the weight.
Lots of confusion on a rv website concerning gvwr and GVWR weight numbers. OP... here's what a auto engineer has to say on the subject;
**I'm a retired auto engineer and Marketing has a big impact on GVWR. As a engineer, it was our job to make sure the frame, brakes and powertrain components were designed well above the GVWR ratings that Marketing wanted, so we would design in a safety factor for each component. You don't really think we would build a truck and then test it to determine what the surprise GVWR number should be!
Axle ratings are also well above the GVWR rating and in commercial vehicles, axle ratings are the pay load determining factor and even they have a big safety factor designed into them.
It would be unusual for a lawyer to accept a overweight case unless it was grossly over the safety factor weight and even then a vehicle manufacture would not share that info because it is not a hard fast number that will break if one more pound is added.
There are many videos of million pound plus loads being moved by trucks across country. It's all about the axles.