Cut the stab holes into the fuselage as small as you reasonably can.
Glue in place with a bead of slow-dry epoxy and micro balloons.
Consider adding balsa crossmembers inside the fuselage to add enough support that an accidental squeeze won't break the epoxy bead.
Masking tape on the stab and fuse sides can be used to control the bead. Remove tape before the epoxy sets!