Weaver’s/Tailor’s bottom is a real thing. Officially it’s called hip bursitis. It is very uncomfortable; take my word for it. The upright driving position in my Land-Rover is one of the few places I can sit comfortably for prolonged periods.
As for Jeeps, my father told me that when the first couple of Jeeps arrived at his base in North Africa during WW2, his C/O regarded them with barely concealed contempt, and dismissed them as “toys”. He instructed my father and a couple of other REME fitter/drivers to take them out and do their best to break them, so that they would have an excuse to leave them behind... So they spent a happy couple of days thrashing the living daylights out of them around the base and across the roughest terrain they could find. Apparently they started out fairly gingerly, and got steadily more and more reckless as their confidence grew. Dad claimed they were impossible to turn over on a loose surface, no matter how quick you went or how hard you swerved. Apparently one did get flipped over because it clipped a rock, but the driver was thrown clear and the vehicle was still drivable once righted, which two of them managed by hand. He thought they were great, much better than any of the lightweight British stuff like the Austin Tilly. They had to report to the C/O that they were very robust and that they’d not been able to break either of them, and because of that they were grudgingly added to the strength.