I hate to complicate the issue but you also can use the Ford factory kit for the wiring. If you look at the back on the inside of your receiver you should see two capped plugs. You can buy the harness and mount kit directly from Ford that plugs into that plug and then use the mounting kit to mount the plug in the bed. These are the parts that are included in the factory 5th wheel wiring kit.
You may not have the harness though on an XL, my truck was missing it as well even though it's a lariat, some sort of build issue but my dealer couldn't replace the harness so I had to use the aftermarket Bargmen T connector.
edit: this is only if you want to have an in-bed plug. I like having the in-bed plug for the camper hookup.