I see manufacturers trucks testing towing capacity around here. I think dodge but lots of them wear padding to keep the spys at bay. Thing is it is a flat trailer with a weight on it, and a big flat plexi screen on front. Doesnt give a realistic cross wind scenario. I assume they do tackle Eisenhower and vail though.
I talked to a hunter a few years back driving a really nice rental because his group burned up a truck pulling a horse trailer. Tranny going up, brakes down. Even without hotrodding the thin air reduces cooling and power.

Back when we knew how to drive dad pulled a big camper with a 63 suburban, 283 truck , granny 4 speed.