This is related to the pantyhose lens and mesh visors issue. I recently tested out wearing a black Nomex Balaclava backwards with no visor for a non-canon event. The local Society for the Physically Disabled was having their annual dinner and it so happens one of their staff was the wife of our resident clone trooper. They even offered to reimburse our transport costs but we had to say no. Even though a couple of us had wheelchairs running over our toes (a lesson for future troops where wheelchairs are likely).
Back to the (non)visor, it seems the eyes don't show up, even under flash. So it should be good so long as there isn't too much ambient lighting coming in horizontally. Breathing was OK, visibility OK, no fogging. Heat was not a problem as this was indoors. I'll test this system with my helmet fans outdoors within a couple of weeks.
Only problem now is that the insides of the helmet might become visible. Maybe I should paint the insides black (they're currently this off-white fibreglass hue, it being a DP).
The "worst" photo, showing bits of the inside, for your viewing and criticisms:
