After calling around to a few different Trek shops and buying several different hangers online, I took my bike to a shop near me that specializes in commuters and things like that.
The mechanic took one look at it, ran to the basement, and came back up with the correct hanger. It is a Wheels Mfg. #49.
I explained to him the trouble I had trying to track down the right hanger, and how it is listed incorrectly on the Wheels Mfg. site. He told me that this hanger in particular is common to a lot of Fujis, so his guess was that they were all made in the same factory, just under different brand names.
Anyway thanks for all the help and research, I'm glad I finally got this resolved.
TL;DR: Wheels Mfg. #49