Never towed with either but owned a 5.3 1500 work truck with the factory tow package (listed to tow 8500lbs) that struggled to pull a 32 Sunsation on a triple axle trailer. Boat is 6600lbs dry, plus fuel/ trailer. After a 3 mile ride to a gas station I never hooked that combo up again.
The last loaner I got was a 4.8 1500 Crew that burned rubber around the block. I actually thought it was a 5.3 until checking under the hood to see it was a 4.8.
I liked both the 4.8 and 5.3 enough to buy either if the deal was right but towing that boat may be an issue for you.