i've seen wires run several ways. one followed the top of saddle bag guard plastic tied in place , or feed wire through top of seat where rider backrest mounts when not in use he tucks it inside, or run wire left side of frame and plastic tie in place
I ran mine down the right side under the seat, comes up at the grab rail and I tuck it between the grab rail and the seat. Works great for the gloves and the battery tender.
I use the wiring for the battery tender. I changed the plugs to 1/4" audio plugs and hard mounted the female plug to the adjustable backrest lever bracket. I use a 90 degree male plug for my heated clothing and it is an easy one handed plug in or unplug.
On my UC I have it coming up through the seat at the driver's backrest. On my work bike I have it coming out at the front of the seat next to the tank, which is the easiest set up, but not as easily hidden.