I pulled a old heavy 24' travel trailer all over with my 77 Bronco with either the 302 or 351W or 3.50 or 4.11 gears. Never had a problem. Proper equalizer hitch and bars, anti sway bar and a good brake controller. Lot easier to spot with the short wheel base too but I am sure that it exceeded the CGVW. The trailer brakes always straightened the assembly if it got out of wack because of high speeds. NEVER picked up the back of the truck.

Bottom line, use good equipment and you'll have no problem. I also used to flat tow my 75 Bronco behind the 77. Always tie the steering on a towed Bronco.