Tom, I have a 8.5' x 20' PACE with 7500# axle cap. See my gallery. I pull it with a short Escalade, 403 HP, 6.2 gasser. Plenty of power, but 9 mpg at 65 mph .. 6 mpg at 75 mph
Going faster than 65 just means extra fuel stops, so you don't save any time. It is a real barn in the windstream, but I love it at the track and away Cobra events.
Regardless of which enclosed trailer you choose, I would not go longer than 20' with that tow vehicle. Maneuvering in parking lots gets trickier as your overall length increases. At some point, you're a semi
Whichever way you go, have a weight distributing hitch installed. Your QX will handle MUCH better, with the short wheelbase compared to a 4dr truck and heavy (800#) tongue weight.
You'll need some towing mirrors for the QX so you can see behind the 8.5' wide box.
Sam