Pykes Creek Reservoir just off the M8 to Ballarat is not a bad site but is in a very cloudy site . Also true for much of the M8 from Bacchus Marsh to Ballarat (often worse even than sites further south) with cloud forming around those hills even when the rest of the state might be clear. Same is true for Mt Macedon.
If you can get north your odds improve a lot. Around Kyneton area is worth a look but unfortunately the public Coliban Water site next to Lauriston Dam is closed at night. There are other roads in this area that look to provide possible spots. I've been wanting to check out this spot but haven't got there yet:
https://www.google.com.au/maps/place/37%C2%B017'13.0%22S+144%C2%B023'53. 3%22E/@-37.2869496,144.3974252,335m/data=!3m2!1e3!4b1!4m2!3m1!1s0x0:0x0
Hanging Rock visitor area would be ok but also closed at night - frustratingly hard to find good spots in this area!
Phil