Basically yes...
Use your existing flat 4 (or you could swap it out for a flat 5 that has the additional wire for the brakes), get a trailer side flat 4 and a quick connect for the 5th wire. Take the pigtail (trailer side flat 4 and additional wire) and wire it to the (truck side) 7 pin you have in your pictures. All you'd be making is a plug in adapter to a 7 pin that can reach the tongue of the trailer. Then when you get where you're going just unplug the flat four and 1 quick connect wire and the adapter stays with the trailer.
I've got a few home made adapters in the shop that I can brake out tomorrow and give you a better visual of what I'm describing.
A better visual would be helpful. I’ll be picking up what I need tomorrow and trying to get it done tomorrow or Wednesday. Thanks for help. Good ideas.
Another one I’m thinking about is drilling a hole for the 7-pin harness in the top of my bumper and that will be that. Just need to make sure I can feed the wires underneath and make it all work.