Not sure who told you she is a lightweight 4x4. I had to weigh mine for my military move last year:
"I did weigh her yesterday. 4420 lbs empty. I took out all parts, tools, sub, backseat...heavy toy for sure"
That was empty tank,no spare and so on.That means, normal rolling weight with me in it is close to 5000lbs. I weighed my 4dr, diesel F250 weighed in at 7200 lbs, and I didn't take anything out at all. So almost twice the truck, not even 50% heavier.
An F150 doesn't weigh much more than the VX, and they are rated to tow 9000lbs. (not sure what the new ones are rated for, probably even higher) Of course, they have WAY better brakes. Wheel base may have some negative aspects, but the Trooper RS has the same rated tow capacity as the regular 4wd trooper.
Like I said, I bet there are DOT tests to be performed for tow ratings, and with so few built, was not practical to spend the money on the testing.