I pulled a 12' U-haul utility trailer from one end of Illinois to the other (the LONG way) and was loaded up at 9600 lb. GCVW on the way back. I was hoping to gross out at 10,000 but ended up a little short. A good part of the drive was on I-39 running 65-70 mph and the rest was rural 2-lane gently rolling roads.
I was
more than impressed with the stability and towing abilty of the Jeep. I was a little nervous since the trailer was bigger than the Jeep, but I never felt so much as a wiggle out of it, loaded or unloaded.
I just took it easy with both accelerating and stopping, and keeping it out of overdrive so it would lock up in 3rd gear and then hitting the button once I was at about 55mph so it would go right into 4th locked up.
With the load on the trailer centered (stoker coal loaded by a front end loader that could fit the Jeep in the bucket

) the back end of the Jeep barely settled an inch, so there wasn't much increase in tongue weight over empty. I pulled down 18 mpg overall, and I think it was actually better mileage with the load! The trailer had some pretty stout bias ply tires and I could really feel the rolling resistance of them. It was bad enough that I actually stopped to see if the trailer brakes were dragging. They weren't, so I checked inflation and one was a little low, but not bad. I topped them all up just to be safe.
I would certainly feel comfortable with even 7000 lbs. behind the CRD provided I had a good set of trailer brakes and a controller, stout shocks and struts on the Jeep, a real torque converter and maybe a GDE eco and trans tune. I have the F37 converter/flash and it did well on the haul, but if I was regularly towing, I'd like something I knew was bulletproof in there. I don't trust that cheezy rear diff, either. Too many "cost reduced" Chinese and/or Indian cast parts and bearings in there to hold up under severe towing heat and torque.