The PoserPros capes would be great if they didn't fold around the neck. Everything I found at Mystic Nights I've already tried.  I think the Dynamic Long Cape would take a little more than resizing to fit.  The shape is roughly 2/3 of a circle.  In order for the cape to drape behind instead of around the arms, it would have to be less than a semicircle (maybe about 1/3 of a circle).  I don't think a square would do either, since it would be hard to curve the top edge around the back half of Mike's neck and still have it look natural.

Any other ideas?