I think you'll have to do mold some epoxy like Old Man said. I wouldn't drill into your stock unless you can epoxy some female threaded rods into it.
A different trigger shoe might help. I've noticed certain trigger shoe shapes position my hand higher or lower in the grip depending where your finger is supposed to fit in the shoe.
For example: the CG Xtreme tactical trigger shoe positions my hand higher than the Bix and Andy smooth curved shoe. Obviously flat trigger shoes will make your problem worse.