Okay, I'm not from Indy but I think I'm onto something here.
Hear me out. They have the same leg striping, blue stripe on helmet as the Indianapolis Colts. The trooper has a lower case "i" on his torso, that could be for Indy. Also, since this one is recognized as the 501st trooper, having the markings be Indy related are a way to say thanks not only to Indianapolis for having CII and CIII there but also a special homage to the "Indy Knights" who are arguebly the biggest LOCAL Star Wars fan site. I said local too. The 501st is not local.
So what do you guys think? Indy trooper or not? Lucas hardly does things by coincidence so...