2 more cents...
I race outdoor nitro as well in the summer. I would never race indoor nitro, the fumes are just terrible and it makes the whole facilitly dirty. On another note, mixing 1/8 and 1/10 on the same track is not a good idea because 1/8 scales naturally just chew up tracks. guys who run 1/10 scale dont really like there cars being beaten up by ruts and wholes in the track. A good indoor track has to be maintained constantly and watered frequently.
Just trying to add some input and things to think about.