I'd cut a nice clean hole with a Forstner bit and then put in a round patch. A strip of wood glued across the back would help hold it and you could fill any lines in the front with any wood putty you like.
Considering that:
1) I am in awe of Dr. Bassman's wood skills, and;
2) I happen to agree with him (usually a smart move);
I like his idea!
Seriously, the "do it right" method is to restore wood in the damaged area. Adding large quantities of filler of any kind is an esthetically displeasing solution, and screws are likely to come loose over time.
The downside is that if this is on the front of the instrument, you'll probably need to refinish the instrument. That might argue in favor of finding a jack plate that will cover the damaged area and extend JUST far enough to give you wood to screw into and secure the jack plate.
PICTURES would help, nudge, nudge, wink, wink, knowwhutImean?