The 4.6L engine is not very large and it really depends on you rear axle ratio. Your 6900 max is based on a properly equipped vehicle, tow package, towing axle, HD cooling. Does your truck have the towing package?
Also, the 6900# is a maximum trailer weight and based on a base model truck, with no cargo, no hitch, no options or accessories and only a 150 driver. You add cargo, hitch, passengers, etc, you reduce the tow rating accordingly, pound for pound.
In short, I do not think you will be happy pulling the trailer with the truck you have. You load and travel light, you may be under on weight, travel on flat roads and say out of the hills, it is doable.
Amateur Radio Operator (KE5DFR)|Full-Time! - 2012 6.7L Ford Crew Cab Dually -2013 HitchHiker Champagne 38RLRSB - Travel with one Standard Schnauzer and one small Timneh African Gray Parrot