It may vary by state, but in the two states I’ve lived in my insurance has always had a 0 deductible for glass only claims. Before you decide to pay out of pocket you might want to make sure that you’ll really have to pay the deductible.
I can’t really help much with your rear window, but I had a stone hit my windshield and crack it and my insurance recommended safelite. I started the process with safelite, but they mentioned that after the windshield replacement I may need to take the car to Tesla to recalibrate the autopilot system. That made me nervous enough that I talked to my insurance and got their ok to just have Tesla do the replacement.
I have used safelite for windshield replacements on other vehicles and I haven’t had any complaints about their service. Autopilot wouldn’t be an issue with the back glass, so I don’t think I’d have a problem using them for that.