For comparison I have a '12 Titan CC 4x4 and tow my 32.5ft (couple to bumper) 7667 lb GVWR ST290QB without any issue. The Titan pulls it with ease and doesn't sway or fade with the WD hitch (unless heavy winds). Braking with the brake controller has been excellent and gas mileage through the mountains is 8.5-9.5mpg. I will say I don't load the trailer with more than 750-1000 lbs of gear beyond its dry weight of 5888 lbs and I also don't overload the Titan (just 3-4 days of light evening use firewood). I never travel with water in the tanks either.
I personally wouldn't go heavier or bigger, but I've read and seen others with Titans going bigger and heavier. The weight police like to discount half tons, sometimes for good reason. However the main limiting factors with any half ton will be tongue weight and payload. Stay within reason and you will be fine.