[davepl]

^^^ This, from a shop with a warranty that's been around for more than 3 years

It's not that it can't be done, but I see so many poorly done ones that I have to imagine doing it right isn't trivial. Maybe its prep, maybe its better product, maybe its skill in application, but whatever it is, I'd pay to have it done.

At least for a single window because that should keep it cheap.

You likely know your laws better than me, but I think California has some fairly strict tint laws (I'd want them too if I was a cop having to pull people over). Not sure if they apply to the rear window at all though. Check before spending the money.