I towed my 7600lbs tt with my '07 Tundra crewmax for a couple of years. Handled it with ease. We were payload limited and slightly over once the family was loaded and some stuff in the box. The double cab has more payload and if it's just the 2 of you, you will be more than fine.
When it was time to trade the truck I ended up getting a Ram 2500 for the extra payload. Worst decision I ever made. I would gladly take my old Tundra back. The Tundra with its 4:30 gears even towed the tt better than the Ram does.
Nice thing with the new '16 Tundra is that it finally comes with a factory brake controller and has a ( optional) 36gal fuel tank. A must if towing.