progressive industries 50 amp hardwire question

I just purchased a progressive industry 50amp hardwire surge protector. I want to remove the cable that connects to the socket on the outside of the trailer. Its kind of hard to reach the cable from inside the compartment so I plan to stand outside the trailer, remove the socket from the outside wall of the trailer and then disconnect the cable from the socket. My question is 2 part. What is involved in disconnecting the cable from the socket and then installing a new 4 foot cable which will go to the surge protector. And how do I reattach the socket to the side outside wall of trailer making it water proof. There are 4 screws securing the socket to the outside sidewall of the trailer.