Yep. Put in at least a 3/4" wide strip of 1/4" ply, extending all the way to the sides of the fuselage. Having the 1/4" ply reinforcement as wide as the landing gear is better. Epoxy it in, and be sure the epoxy is glommed up on the ends as well as the major face that touches the bottom.

You'll be happier if you drill it a little large and use Tee-nuts. 6-32 screws are usually about right.