I saw your post at PBC Killer.
My mask fogged a lot too so I decided to try to do something like you did.
I bought two 1 inch (25mm) 5 volt fans. I mounted them with zip ties.
I did basically the same thing that you did, but I only used one 9 volt and a put the battery inside the mask. I'll try to get a picture of it...right by your cheek bone there is extra space and I just zip tied a 9 volt in there. I covered it up with electrical tape so I wont get shocked when it rains