I have a 11' WK2, V8 4x4 Overland and I've used it to tow a 18' toy hauler with a RZR XP in it.
I think the dry weight of the trailer was around 4,000lbs, plus a 1,200lb RZR, plus ice chests, gas, firewood, food, etc. I'm guessing I was in the 5,800lb range.
I also had the weight distribution hitch and brake controller. The Jeep did pretty good towing. I set the cruise at 70mph from Phoenix to Glamis sand dunes. There were some downshifts required through the hills, and got an average of 7-8 mpg.
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