Running wire to Pin

[Kahoneys]

I am wanting to run wires from the rear of the 5th wheel to the pin to hook up generator and 4 wire to receiver. I can run them on the underside on the main part of the trailer but want to hide it on the underside of the 5th wheel. I have a great spot to put the wire up under the cap but cannot get my fish tape under the fiberglass to the pin. I removed all the screws on the underside thinking it would help but to no avail. Does anybody have a idea how to do this?