^I agree with this guy. (and not just because of his name)

I've towed another 4runner behind my own on a dolly. But I also have the 13WL brake upgrade already and the external tranny cooler.

(Unfortunately for me I am a 97 so I can't see my trans temps)

The air supports would be nice, but not required if you're just running a dolly. Most of the weight would be on the dolly tires and the other set on the ground. I do wish I had some last weekend when I was hauling some motors on a flat trailer that was making the rear squat a bit.