The Ecoboost is rated at something like 11,500 pounds maximum, but that is when there is no passengers in the truck, nor cargo in the bed.
Your GCVWR is 15,500 pounds. So lets say the full truck before hitching up is 5,500 pounds. That would mean you can tow 10,000 pounds. Yet if you plan on adding 500 pounds more to the truck in passengers and cargo, then reduce the max trailer weight to 9,500 to stay below the 11,500 GCVWR.
And the second thing to consider is the truck weight loaded. Your GVWR can be anything between 7,200 and 8,200 pounds, depending on the cab style, if you have the max towing and max GVWR options. If you have the 8,200 GVWR, and the empty truck is 5,500, you can handle 1,000 pounds of hitch weight, 800 pounds of passengers, and even add some firewood, to give you a total of 7,300 on the truck tires, still well below the GVWR. Then consider the trailer has 8,000 GVW, you do not need to add the hitch weight twice.
Fred.
