I own a 2001 Suburban 1500, 5.3, 3.42, 4x4, since new. 124,000 miles.
Times I wish I had a crew cab. Though I love my "warehouse" in back of the 2nd seat that is weather proof and climate controlled. When we went upstate this year to buy a Christmas tree we just tied the tree to the roof rack. That warehouse worked well for we were able to keep our beagle in the back while we ate. If we had a pick up my wife would put me in the pickup bed before I could do that to her dog. Cap or no cap.
I had bought a 4x8 Harbor Freight trailer for the times I had to haul dirty stuff or something to big to fit in the Suburban.
Now I only towed a Coleman pop up. I never felt it in the back. I was able to do 70 - 75 mph and get 20.7 mpg.
My towing capacity is 7,900 lb.
Now it would of been higher if I had gotten a 3.73, and higher again with the 4.11. Though I knew I would never be towing more then 7,900 lbs and wanted best fuel mileage.
With Suburban's 2001 and up once you went 6.0 mpg dropped a lot.