See if 3M still makes blasting tape,it's 2" tape but more like dense cardboard.Tape off the glass,lay out your lettering and cut it out of the tape but make sure the edges are stuck good.Now lightly wave a sandblaster over it to etch it.I've done this and it looks just like fine glass etching but I've never painted it.Of course going back is out of the question.Sure you don't want custom decals?