snorris-
I have a hawk shell model on a 2011 Tundra Doublecab and it drives great. The only mod I did to the suspension is I had the rear springs modified to handle the extra weight without air bags or sway bars. I didn't want to change the off-road abilities of the truck. Boise Spring Works in Boise, ID did the work for about $500.
Since I had the Hawk installed I have driven about 3200 miles in ID, WY, CO, and NM. I have driven lots of windy mountain passes on pavement, lots of fast gravel roads, and lots of off-road on two elk hunts. The vehicle drives great in all conditions. It feels very secure and in control on the highway and rides and drives great off road. I am surprised at how unnoticeable the camper is while driving.
All that said, if I was going to get a new Truck for the camper I would not get the Tundra for two reasons. First, Tundras are one of the worst gas mileage (and range due to small gas tank) full size pickups. Second, other even 1/2 ton trucks such as the Ford F-150 have higher carrying capacities.
I only kept the Tundra because I already owned it free and clear. It does drive great with the camper so I'll probably keep it.
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