I frequently see drivers run stopsigns, speed, and fail to make proper signals for lane changes - no legal issues UNTIL they get caught by a LEO or involved in a accident!
Comments as to what you SAW someone do - or manage to get away with yourself have no bearing on what is reasonable, proper, or legal.
Our 24 ft 5er has a WEIGHED pin weight of 1200 lbs. My in-bed hitch weighs about 100 lbs, and my 50 gallon fuel/tool box adds another 500 lbs or so to the mix - for a total bed weight of about 1800 lbs - and that is without passengers and miscellaneous other camping gear added in. My truck itself weighs 7000 lbs, according to the local DOT scale.
As I read and understand the GVWR for my truck, it is rated at 8800 lbs total - subtract the 7000 lbs the truck weighs, and that leaves 1800 lbs for cargo - right about where I am with a 7000 lb, 24 ft 5th wheel!
I'm well under the GCWR for my truck, even though I'm already at the ragged edge of my truck's GVWR.
In a campground, around a campfire, you probably will get away with (maybe even applauded!) bragging about hauling a 33 ft rig on a truck like mine, with a hitch weight up around 2500 lbs - but how loud would you brag in a court of law, perhaps in the company of relatives of the folks you killed or maimed?
The legal consequences, to me, simply aren't worth it - as one of the "senile older coots" mentioned earlier, my reflexes and eyesight just aren't what they used to be. And it seems pretty selfish for ME to place others at deliberate risk simply so I can indulge myself in my chosen pastime - at the same time twisting rationality as a tool to excuse what I am doing.
If my truck is clearly inadequate and unsafe for my desired load, I'll park it - and God help me if I deliberately endanger my equipment, or the lives and equipment of others simply to indulge my own selfish wants.
The bottom line message for this thread, and the previous dozens like it is,
get enough truck for the load, and the question doesn't even need to be asked or debated.