Now that I've got the window done I am doubtful it will ever get made like the original, so perhaps a modified version with a thin slot on three sides for a chunk of plexiglass/perspex would be good enough. I could also merge the window piece with the door, but then you wouldn't be able to use an original window if you find one.
Also, if the door is too hard to print as is, I could pull the guides off. Do it as three pieces, and glue them together afterwards.
If trim isn't available, the window could be redesigned with that area filled in and perhaps embossed with some text.