You are right that is the published limit for your truck. There is very little chance you will actually be able to legally tow that much though (or honestly want to but that's another story). The real number you need to be looking at is GVWR. This is how much total the truck is allowed to weigh according to Ford. I've got the same truck so I happen to know your GVWR is 7050 lbs. This means, that no matter what your truck can't weigh more than this.
So, lets say gassed up truck weights 6050lbs. Add 500 lbs of people, gear. That means you have 500lbs left. OR your tongue weight max is 500lbs. This usually transfers into ~ 5000lbs trailer. Boats are tail heavy, tongue light so it could be more. The only way to really tell is to load everything up (including people, gear, gas, boat on trailer etc) and take it to a weigh station.
Also, note the axle load limits. The weigh station will tell you the weight on each axle. Those limits are published by Ford as well and you do not want to exceed them. (When you go to the weigh station, have the boat attached but do not have the trailer axles on the scale)
Also, regardless of all of this, with a class III hitch, over 5k load requires load leveling. If your right around the 5k mark and the truck drives well, I wouldn't worry about it.
Hope you don't mean me. I love Fords. Just stating the fact that Ford, and all the other 1/2 manufs. publish max tow loads that are near impossible to actually legally achieve. They are based on the most stripped down, lightest truck in the production line. The one that almost no one actually owns.