Thanks, just for an update on this, we decided to rent for a while, and took a Nash 25c (not ideal) from Seattle all the way to Yellowstone and Glacier. The trailer loaded was about 6200lbs, so within the 7200lb tow rating, and we used an equalizer 4 points wd hitch and prodigy bc. We did everything from broken roads, to long stretches on the plains with 40mph crosswinds, and did some nice long steep sections, including the continental divide.
So, this combo worked, but it wouldn't recommend it . The Nash rides high, isn't that aerodynamic and has a bouncier off-road suspension. The weight itself was fine..the diesel has plenty of torque (455) so pulling was never an issue, and was great for engine braking too. Going steep uphill on the long I-90 stretch over the divide, the little engine was working hard I had to slow to 50mph in sections (normally kept at 60-65). Trailer sway in crosswinds was noticeable, but the trailer mode in the AWD corrected everything nicely. Rain, thunderstorms, no problem, just slowed down some.
Oh, and I averaged about 13mpg towing (vs my normal 30 highway, not too shabby). I would NOT do this with a gas model. The diesel makes a huge difference. Note that the Jeep Grand Cherokee is basically the same thing. I have to say, was pretty funny seeing the occasional guy in pickup truck gasp as we passed them :)
Bottom line, I'd say a 4500-5000lb dry trailer is fine. I would make sure it has a proper (not bouncy leaf spring) suspension, and rides lower to the ground. It's a modern SUV and needs a modern trailer to go with. Airstream would also be great, but they're not family friendly (we need a bunkhouse.
