I have a Tundra with a 6.5 bed double cab and a Hawk. As Otto showed, the Tundra double cab and Hawk is a nice set-up. You can identify the double cab easily as it does not have a horization door handle for the back seats. I think the double cab is plenty roomy in the back seat. I had leaf spring upgrades done at Boise Spring Works in ID when I picked up the camper. I wish my Tundra had a larger capacity gas tank.
I have the same truck, camper, and springs by Boise Spring works. It's a great setup. I believe the Tundra Double cab with the 6.5 ft bed is the smallest full size truck with 4 regular opening doors and a 6.5 ft bed. That's what I like about it. Good balance of off-road capabilities and size. Granted, the rear seat doesn't have as much room as the larger cab trucks but that is what minimizes the overall and wheelbase dimensions.
I added a TRD pro suspension which greatly improved off road capabilities and a transfer flow 46 gal replacement tank which is incredible. The stock 26 gal tank was horrible for a vehicle getting 12 mph with the camper installed. Apparently a 38 gal tank is avail on the new tundras.