Stumac also sells a tool that cuts the wood around the truss rod at the nut end so that more thread is exposed on the rod and the adjuster nut has some thread to secure itself onto.
I wouldnt want to suggest something that may not work as easily for you but I have removed the fingerboard on an sg special I bought years ago for $60. The rod was stripped at the adjuster, new brass adjuster nuts would just strip out.
I used a sharp chisel and balpeen hammer, with the chisel angle down so not to dig into the neck. Once I got down to the neck it came off pretty clean.
The hard part was replacing the fingerboard without damaging the neck finish on the sides.
After locating the fingerboard I drilled small holes through the fingerboard dot counterbores and into the neck so I could easily relocate the board in the same location, then shaved the board, checked fit, shaved, checked until I was happy with it.
When glueing, the toohtpicks held position. When cured I dremmelled the picks out and covered with the neck dots.
An alternate method would be much easier, but this can be done.
This was about 18 years ago. I put an ebony fingerboard on and installed 3 P-90's, then I think I traded it for a reissue 4X10 bassman.
Cork