[EC900]

Sounds like a BB hole, the back side being blown out is a good indicator. Secondly this hole will likely spider from road vibrations. I would lean towards using the cracked windshield repair method that may hold up better to weather and heat. Probably be best to remove the lens to try and fix.
Another option would be overlay some of that clear stone guard paint protection material, just about anything to keep debris and moisture out.
Then start the searching process for a replacement lens.