I have a 2011 F-150 with the 5.0. I didn't like towing with it. It seemed to wiggle around to much. Then one of the origanl tires went bad at 20000 miles. :M After that I put decent tires in it and I love it now. No more wiggle
I know this had nothing to do with engine sizes of tow ratings. I just wanted to say that some of the original Ford products come from the factory with some terrible tires.
My sister in law has had the same problem with her Ford Edge vehicle. She loves the car but, hated the origanl tires. When she traded her first Ford Edge in on her second she made them swap out the tires and kept the (almost new) tires that she had put in her old Edge.
Check out how good of tires you are getting on your new truck before you buy.