Just my opinion:
Pushing a TV to it's limit is very definetly taking away from the life of that vehicle. It's also prone to cause more white knuckle driving.
You may also be surprised that the gas mileage for a big engine in a full sized vehicle is often better than a smaller engine in a smaller vehicle when towing the same weight. The reason is that you are pushing the smaller motor much harder than the larger one.
I started out towing with a 4.7 V8 in a full size Chevy 150. When I went to a 5.4 V8 in a Ford 150 the difference was astonishing as far as power and smooth shifting goes, and the gas mileage stayed about the same. I'm picking up my new FC23FB in a couple of weeks. It will be about 1,500 pounds more than my old trailer but still 1,5000 under GVW.
I say overpower is much better and easier on your TV than being underpowered and pushing the GVW.
Matt & Virginia Kline
On Nueces Bay, near Portland TX
2016 F-350 6.7 Diesel (Overkill and loving it)