I got down to 7/16" for my tunnels before I stopped wearing them, since they have actually shrunk down to a 8g. Im sure they would have gone further maybe even to a 12 or 14, but I did some guage jumping during my stretching and there was some scar tissue build up.
Ive been shot in the tunnel before, its a very very unpleasant experiance, and if your wearing metal flares, its possible to bleed.
Personally I think you should just keep it a single piercing, snake bites are kinda cook, but I myself cant see them on you, symmetry can be nice, but your single off center is way better.
Your rebuild of your kit seems to be coming along nicely.
"Its only a little bit on fire"