I have been using double tint on my rides. Privacy and heat rejection are priorities for me, and super dark isn't what it used to be as in the early 90s ;)

Also, taller vehicles allow more external visibility. Because the windows are at eye level, chances are, you can see through the tint and to the other window somewhat. For shorter vehicles, since their windows are below eye level, there's not much external light because it's the color of the upholstery that you're seeing and that's usually not bright enough to make you see what's inside the car.

To the TS, if you're vision is good, you can add another wraparound layer. If not, then you can add another layer to the rear windows.