Sounds like it would make for a beautiful extention to your patio. This is a ? for the experts. I'm still learning. I'm sure you will find the info you need here. Good luck.

Maybe add another layer of clear glass as a protective covering / barrier?

I am going to do my first glass on glass this winter to add some art to an oval widow up high in my living room. When was the last time you saw silcone melting in the sun?
Ive never used silicone. I use wellbond for everything I do. I dont think any of the commonly used cements will be effected by summer sun.

Clear outdoor silicone adhesive, that's the ticket!