Here are the horizontal stabilizer tips, also bad with pin holes. But you can see the aft portion of the tips where I closed them off. The HS and the VS tips all needed to be "closed." You can see earlier write ups that have details about that process. But briefly:
1. I epoxied thin foam (about 1/8") to the inside of the tip.
2. Did a layup on the inside of the tip.
3. After that cured I dug out the foam leaving the thin layup and about a 1/8" depression.
4. I filled the depression with a slurry of epoxy and microballons.
5. Covered the slurry with a layup of 3oz fiberglass for additional strength.