That doesn't count. Any bumper pull, especially on thin wall tube bumpers (they all are thin), is going to be weak.
I have towed KJ, MJ, xj, TJ, and various small cars behind an xj and an MJ.
Latest one was a complete 02 KJ behind a 99 2dr 5 speed xj that was stroked and had a 242 on it. It was out of necessity.
Had to take the interstate for about 10 miles. To make this work, I could not use 5th gear, I had to be in full time, and I could not go past 55mph. Also slowing down required much downshifting, though the brakes seemed to be working well. No trailer brakes either.
But I've also rear ended someone going 2mph in misty conditions coming to a stop using that dolly, a 97 xj, and an MJ with 4.10 and 35" tires.
It's all in the conditions on the road, and taking it verrrry slow. Even then, they are still under rated.