I'm towing a 2011 Rockwood 8285WS with my stock 2012 F150 EcoBoost 2X4, Heavy Duty Payload package and it tows like a dream. I had a 2006 F150 5.4L and it struggled with this Fifth wheel, and I had to put Firestone air bags on it. The 2006 was just not enough truck.
Here's a picture of our setup, notice there is very little sag. The rear only dropped 2" after hooking up. The Heavv Duty Payload package helped there.
Now lets look at the specs. The truck has a Gross Vehivle weight of 8200 lbs and a payload of 2413 lbs.
I weighed the truck after I had the FW Hitch installed, full tank of gas. It weighed 6260 after adding 100lbs for the wife.
I weighed the entire rig before our first trip. I wanted it to be fully loaded with all of the stuff we normally take camping plus a 2/3rd full fresh water tank.
If you do the calculations you will see that the truck without the FW weighs 6260 lbs. the truck with the FW weighs 7920lbs (3460 + 4460) which gives me a pin weight of 1660lbs. 1606lbs + 7340lbs (trailer Weight) = 9000lbs well under the 11300lbs towing capacity.
The truck has a max gross weight of 8200lbs - 7920lbs (fully loaded truck and trailer) leaves me with 280lbs to spare. Not a lot but enough.
As you can see the F150 EcoBoost with the Heavy Duty Payload Package
is well equiped to tow a lightweight Fifth Wheel