If you just want white, use shoe polish. It's fine on glass, idk about on paint.
There's paint pens that most impound yards use, and it comes off with a razor blade. Absolutely no damage to the glass. You can also write on the paint, and it washes off with a regular car wash.
I've used the uni POSCA markers extensively, and they're great. One thing to be careful of though, is writing on a hot surface. It'll "cook" the tip of the marker. On the POSCA markers you can just pull the tip out, flip it over, and put it back in. By hot surface, I mean glass that's been in the AZ sun all day in the summer.
uni POSCA marker - Google Search