It turns out that there is no power connection that is running under the right rear side big trim panel on the interior. I did find behind the right wheel on the outside and underside of the vehicle a removable plastic panel. Removed the panel and I found a female plug that has 4 wires to it that have the same colors and the 4-flat trailer wiring connector. I used a volt meter and this connector has no power to the connector, even though it appeared like it would have power, and light connections.
Our local public library has a subscription to Chilton's and Mitchell's manuals and after viewing both I found that Ford uses a trailer module that IS located and wired and mounted on the interior side of the wheel well and behind the trim panel. The power to this module is protected by #78 fuse in the fuse box and the fuse box is under the engine hood.
When I viewed the location in the fuse box (this is a double-layer fuse panel and is not one of Ford's better ideas because of the heavy wire cables going into it) and viewed the second fuse layer I found the #78 fuse position. But only one side of the pocket had a female terminal for the fuse pins; the second pocket did not have a female terminal, and I assume the wire was also missing. So Ford must leave the connection and the wire out of the harness to save money.
After seeing Ford's asinine logic to make life as difficult for the owner as possible, I decided to go back to the original plan of using Curt's brand wire harness for this vehicle. There is enough power wire in this kit to run from the vehicle rear and follow a factory wire harness that routes near the left rear wheel well ( must remove the long underside fiberboard black panel on the driver side). From there it is easy to make a jump over and route along the gas and brake line bundle, which has an open spot on the plastic loom that the power wire fit nicely into, and along and under the driver side foot-well and along a factory wire harness that runs up to the battery area. I used heavy black wire ties from Walmart to tie to the existing factory wire harness and at any other sensible points. I allowed wire slack along the way so that the wire did not get pulled too tight. After crimping the Curt fuse holder to the power wire and connecting to the battery, I went to the 4-flat connector and confirmed the lights worked. (I did use a wire a sheath cover over the entire power wire length as added outer covering protection.)
It took about 2-1/2 hours to do this from start to finish, but I am picky about things like this.
I have seen YouTube videos that just allow the power wire to lay on the black panel, and I thought that was a really bad idea since the wire is always "hot".
I wish Ford would get smart and make it friendly to do a job like this. I found no instructions or easy do-it-yourself kits from Ford after lots of research, only a kit for an Escape and it was from 2006. My son added 4-flat trailer wiring to a 2014 Nissan Frontier and just about all the wiring was in place in the factory harness and, except for a few relays and a plug and play wire harness in the Curt kit, it took about 30 minutes to install. Ford keeps missing the mark when it comes to the DIY people.