I am not sure I like the sound of snow-like weather when certain members of the family are adamant about camping. Where are you planning to stay for NSW Champs?
At a motel in Lithgow - not cheap but I didn't fancy camping either given the forecast.
Wise - the camping ground at Lithgow is built in a windtunnel - last time I was there (WMOC) the tent collapsed, the poles broke and I caught a cold.