I had a 1982? F250 light duty, cast iron I-beams but a F150 rear axle. Single cab. 300 cu in straight 6 cylinder. 4 speed granny gear. Bought a 3rd hand cabover from a co-worker. Tejas 8ft., wood framed, aluminum siding and roof. Almost turned it over in Oklahoma. Put helper springs on it, maybe Helwig, Sears, or JC Whitney. Went all over...Yellowstone, Colorado, Arkansas.
I had no clue what a Cat scale was. Never weighed it. I'm sure it was overloaded now. When I sold the truck, the trans synchros were gone and the rear axle was whining.
One thing I do know, I was not the first, or last, 32 year old that just "did it".