Normally, undercarriage cable running isn't that big a deal. Same goes for most undercarriage through firewall to dash. The biggest problems comes in when running cable from undercarriage to the rear, especially when the cable snakes up through the RV's body. If you have a chase or places to conceal the wires, that's great, but, if it's finished with no place to hide wires, it can be a problem. What complicates that part is not so much the wires, but the connectors. Those connectors can make fishing wires very difficult.
So if you can explain more about the wire runs locations and conditions, that can help with advise. I have run new wires and I have replaced wires. I found replacing so much easier.
