I used to image from Mt Donna Buang in the mid to late nineties. At 1200m altitude seeing was excellent, there was some light pollution but from what I recall the visual limiting magnitude was around 6.0.
I wouldn't be surprised if the visual limiting magnitude is unchanged, Mt Donna Buang is sufficiently far away and more importantly higher than Melbourne's expanding light dome.
Back in those days of emulsion astrophotography and manual guiding, there were occasions when I would do 1 hr+ exposures stuck at the eyepiece in the dead of winter. Not a very pleasant experience.
The other issue was to explain my motives to the occasional police patrols in the area. Since none of them had ever heard of astrophotography, it must have been a very strange sight.
Regards
Steven
http://users.westconnect.com.au/~sjastro/small