There won't actually be any parts on the outside of the helmet. The "nut" part of the Chicago or T-screw is attached to the inside of the helmet, and then the visor ( with the holes for the nut ) slides over that, then possibbly a washer, and then the bolt part. The visor material should be sufficiently dark enough to keep anyone from seeing in.
The Chicago screw nuts DO NOT go through a hole in the actual helmet outside to inside, if that's what you might be picturing. Check back earlier in this thread for diagrams.
Hope that helps.