You know, I had the same trouble when I was looking for references of Mia. I would suggest either playing the game or looking up game play videos, and pausing it until you can see the back of his costumes.
Like this: http://www.youtube.com/watch?v=L_GgdMbfsZs
I'm sure you can find a better quality one.
The only other suggestion I would have would be finding a cosplayer who has cosplayed him and asking for a picture of the back of his costume. (Though they might not even know, they might have just made it up.) Good luck!