Unless you are going to a 3/4 ton truck you should keep the Tundra. You're not gaining anything going into another 1/2 ton pls it's barely broken in.
Your Tundra should have no problem towing that trailer with E rated tires on it. You may be a bit over the (under rated) payload but you'll be well under the axle ratings. As an engineer you should take a look at the components and their individual ratings and you'll quickly see that the Tundra is capable of safely handling more than what the lawyers rated it for.
I towed the trailer in my sig (34' and 7800lbs) for 2 years with my old '07 crewmax without issue. A couple hundred pounds over payload but under the axle and tire ratings. I eventually traded up (or so I thought) to a Ram 2500 Hemi with the thoughts of a better towing experience. In my experience, the Tundra towed better and was much more reliable. If I wasn't planning a fiver in the future I would have another Tundra.