have someone do it for you. shudnt cost to much. any luthier cud do it
Monkey-grip on a Strat? Not one I've seen before actually. A router is the best solution, and possibly the only one. In theory you could drill it out with large bits and then get rid of the excess by hand, but somehow I can't imagine that giving good results - I chiseled out a pickup cavity by hand the other day and after two hours' hard work, it still looked like a bomb had had gone off inside it...

Are you refinishing the guitar too? If not, you'll have one hell of a job trying to finish the inside of the grip.
a router bit
a drill press
a jig
some power bait
and a sasquatch costume

the last two are just for fun but deffinately the first three!
Out here you've gotta know where your towel is!
ya im gonna refinish it. i think im gonnna drill out some spots, then use a hand saw to cut the rest.
router and drill, jigsaws are more likly to burn the wood and would be harder to keep the depth and right angle

id prob go with a drill press to get most of the material out and then go back and finish it up with a hand router.