I had this happen to me on the road a few years ago (previous trailer, non AS.)
My first thought was to just try and do a splice job on the side of the road to keep going (I always carry lots of tools, soldering iron. etc.) But in the end I was able to carry on down the highway with no brakes or lights to an RV repair shop where they were able to replace the whole cable and plug right back to the junction box - a much better resolution.
They did this while we had lunch and we were on our way again within a couple of hours.
Don't recall the cost but it was very reasonable - certainly not worth my while in some car park with a soldering iron and shrink tubes trying to splice the old cable! I think it might have cost me around $100 total.
On the Airstream though, I'm not sure how easy it is to get to the junction box with the belly pan being there.
The longer I have the Airstream, I have doubts about how good and idea that belly pan is, especially if you need to get at waste tank valves, wiring, etc.
As well, with the salt we get on the roads up here, the rivets are always rotting away and panels starting to drop down - I seem to have to replace rivets (adding large washers due to the corrosion of the panels) every time we take the trailer out!
EDIT - OOPS, SORRY, THOUGHT YOU WERE TALKING ABOUT THE 7 PIN
UMBILICAL CORD !
Brian & Connie Mitchell
2005 Classic 30'
Hensley Arrow / Centramatics
2008 GMC Sierra SLT 2500HD,4x4,Crew Cab, Diesel, Leer cap.