I did this on a 2010 F150. The wiring should already be there to the back of the truck. You add a harness for the 7 pin to the factory harness (plugs in ), get the harness connector for under the dash for the P3 (plugs in), add an oil cooler for the transmission, and mount a hitch to the frame, unless your bumper is rated for what you intend to tow.
You probably also need to add a couple fuses in the block under the hood to allow trailer battery charging etc.
I agree, e trailer is the best for trailering parts and they have videos for almost everything they sell.
2014 F 150 ecoboost
2008 Chrysler Aspen
09 Amerilite 21 (modified)
2013 Bendron 14' enclosed cargo
2011 4x8 open cargo