I agree with aidlook.
Cut the body like that, and get a wraparound bridge from guitarfetish. I used one just recently, and they are very good quality, especially for the price.
Fill in the humbucker routs and try again. To fill in massive holes like that, use polyfil (drywall filler and a router to give it a smooth bottom, then cut a matching plug (to the body wood) and put it in). After doing that, just use rails to make a new route for the three humbuckers again, bit this time use a pattern bit to follow the rail, and you'll have a nice square cavity to use with a pickguard.
The guitar is definately not beyond repair, but will take work to get a decent finish. The key thing to remember is that no matter how hardcore or extreme the guitar is, it's still got to be clean cut and well done to be a good guitar (examples: Neil Moser or even MetalMatt from our forum).