On my 2014, I brought my wire down one of the gray tank vents. I drilled a hole sideways at the top and bottom, then ran the wire out and across the storage bay to the location near the batteries where I mounted the controller.
Another member here wrote about fishing his wire down beside the vent pipe, which I would have preferred. But my unit did not have the open vertical space beside the vent pipe that his does, so I had to drill.
Hope this helps.