That looks like a lot of work; most of the damage is not visible. I don't know planes, but if this were a boat I would say that you have at least four compromised bulkheads and a whole bunch of stringers that need to be replaced. The big problem is going to be doing this with all of the wiring bundles in place, you can get it all back together and spend a year chasing gremlins caused by wires damaged in the repair process. Of course, in your world you can't simply tow a plane back to harbor when the electrical system fails.
I recall that many years ago a certain type of wiring insulation was used that degraded after X number of years, and a lot of planes became uneconomical to repair.