I'm deep into a '61 Safari rebuild and I am starting to think about the electrical. Everything wood in mine was wasted including the sub-floor, so gutting and pulling the interior panels was a no brainer for me. 80% of the space in the walls was a disgusting mess left by the forest creatuers, but the wiring doesn't seem that bad. (I'm still going to replace it.)
Your exterior is filthy but the inside looks pretty clean. If your subfloor is solid all around the edges and you plan on keeping the interiors, I would certainly see if the wiring will work as is before tearing everything down.
My blog: 61' Airstream Safari Rescue & Rebuild
P.S. Here's something scary the trick or treaters found in my haunted Airstream last night!