Drew, The trigger-guard is right at 1/2" wide so a big channel can be cut underneath it with an end-mill once the stock is secured in a vise on the table of the milling machine. The channel should be just a tiny bit narrower than the trigger-guard so the repair is completely hidden. You can go from the head all the way through the wrist to the end of the trigger-guard if you need to.

If you have the book "Shotgun Technicana" by Mi hall McIntosh he shows the process. The big spline provides the strength instead of dowels and pins. It can be 7/16" wide 1 1/2" high and 6 inches+ long.
I have even used it proactively when the wrist was weakened by a bark inclusion uncovered when converting a stock to a straight grip.
Obviously some re-inletting is in order depending on how extensive the spline is.
The Titebond makes nearly invisible repairs and holds everything together for the milling process.
Once that's done and the big wooden spline is epoxied in it's rock solid.