I would agree, that too little hitch wt was probably the cause. Been there done that pulling my bobcat with my MDT dump truck. Has ZERO hitch wt, and trailer was moving back and forth. Moved the bobcat forward so I had the typical 800-1000 lbs HW for the total usually in the 7500-8500 lbs tween axel and HW depending upon tools, extra bucket and fork attachment I sometimes carried at the front.....Pulled straight as an arrow.
BUT with that in mind, the truck does look 1500'ish IMHO. So probably a bit over tailed for my sence of well being.
Here is my combo with the 2800 lbs mini trackhoe, bobcat....usually about 10500-11K on the axels, 1400-1600 hitch weight! assuming the link works......
