I also await a answer from the pros. I have the 4.6 in my Explorer Sport Trac. Granted, the Expy is a lot more heavy duty, but the gear ratios are the same and my 20MRB is under 6000 lbs.
Just because the Expedition is a heavier vehicle, does that make the 4.6 more powerful?
EDIT: Just researched and the max towing weight for Withrow's Expy is stated at 4,000 pounds!
So, will it tow his 7500 lb. trailer. Sorry, no. Very under powered. Short of stuffing a 5.4 engine in it, no modifications will alter the tow rating.
2015 White Hawk 20MRB
2011 F150 Non EcoBoost (5.0)