Okay, so now it is done!
-:- AND -:-
You can download it!
Yes, I went and created a Troop Sleeper car as a unique car, so that it could show a different paint scheme from the regular Passenger cars. This way, you can tell which of your trains are pulling soldiers on the main screen! I still haven't figured out a way to add cars, though, to the 2D interface; this is because there is one big image file that includes all of the 2D car sides, and there isn't room for more stuff.
Still, you might just want this for cosmetic reasons:
Go check out the full lineup on my web page (scroll down to the Rolling Stock section), and if you're brave, click on the download link and see it in action. Installing this mod, of course, will change a few files so please BACK UP any files before you over-write them!
I promise more downloadable cars will be coming in the next week or so.