I have not heard anyone doing this. Couple things I would look into first.
What is the roof structure like; I would contact Jayco and ask for the roof layout schematic (have your vin # handy). This will give you an idea how the roof is built. If you have a roof vent in the right area, might want to remove the inside trim, to also view the structure. A few people on other TTs have framed in a new roof opening for a second AC unit.
Wiring; Assuming you have an arched trussed roof, you can pull a new wire. It will take a bit of effort to figure out the routing. Pending on your frig, you might be able to snake over to something like the frig access panel and then down to floor, and follow the rest of the utilities. Another option, assuming your bathroom is like mine. The black tank vent pipe runs up along side the wall in a corner, and has a piece of wall board covering it at an angle. Should be fairly easy to remove this wallboard to transition from the ceiling to floor level.
Another option, not as pretty, could run plug-mold up the wall, and over the to the AC. I just did some in my garage and hated working with it.
My roof top unit has 12 gauge wire. Fairly stiff stuff, which will add a little additional challenge to the project.
Let us know what you do, and post a number of images.
2012 Jayco X23B
2020 Ram Laramie 3500 SRW Air ride 50Gal fuel tank.
2007 Dodge Dakota Quad Cab (retired from towing)
Equal-I-zer 4-Point Sway Control