I got an email from Marti today that follows up the question of why Ford is only offering a few years of Fox Body Mustang window stickers. See: https://www.hagerty.com/media/news/ford-will-reprint-window-sticker-for-1987-89-fox-body-mustang/
Answer: Because Marti is offering 1987-1989 themselves, and say that 1990-2006 Mustang is coming soon.
They have all 2007-2017 Ford, Lincoln & Mercury as well which I guess is new? [Marti is well known for having the older FoMoCo stuff].
Is there any company that can make such sticker for me? I am planning to order stickers here: http://urbansignandprint.com//collections/sticker-printing . It seems like a very good company which produces high-quality stickers.