Borderline sketchy.
looking at your sig line, you have the power. That is rarely a problem with a Bronco. But engine cooling often is.
'76 should be front disks, probably OK there.
Bronco is a great boat ramp truck.
From experience towing my 16' boat on 33s, not the best idea. Short drives, low speeds, probably OK. Stab the brakes coming around a twisty corner, it will turn you around and ball the whole rig up in the ditch.
I'm not going to say no, but I am not going to say it is a great idea.
Factory tow rating was either 1000 or 2000 pounds. Larger tires and lift decrease the capability, a rear sway bar does not bring it back. I doubt the boat is that light, maybe dry empty weight, but not wet loaded weight plus the trailer itself.