INFO: Rear Window Seal for Fastback

I agree that R&Ring the rear or front glass is risky. I would only let someone do it that I knew was very good at it.

That being said, it's common for any fixed window to have a water leak, the seals get very hard over 10-20 years. I have carefully smeared Ultra Black RTV along the top edge of three of my SUV's rear quarter glass windows.

If you could get at the entire interior glass perimeter, you could seal that up from the inside, and not be visible. On the outside you might choose to carefully tape along the outer seal, and then apply a thin coat of RTV. I like the Ultra Black etc, because it can take any kinds of weather or sun, and last forever. I have it on my house chimney to seal cracks in that cement, it's held for 15+ years so far.