If you can move the stab side to side enough, you can re-glue the old joint. Slide it over and use a T-pin to make small holes on the old glue line. Do that top and bottom. Bend a T-pin at the end and use that to puncture the old glue line on the fuselage. Mix a batch of slow curing epoxy and glue it.

If that won't work for you, you can install round toothpicks through the fuselage and stab. Use a slow cure epoxy here as well. Drill the toothpick holes so that the pick is snug. Before the epoxy cures, cut the toothpick flush with toe nail cutters. Wipe up the excess epoxy with a paper towel and denatured alcohol. Use a hole punch to cut small circles of the matching Ultracoat and cover the ends of the toothpicks.