I can try to organise a get together from mid October but I am a bit limited as I will be os from 4th August for 8 weeks till end of Sept.
However I have some suggestions that you can think about or provide alternative suggestions.
Option 3/ I am prepared to host this
orgy bbq at my house with the usual proviso, you either kick the door or hit it with your elbow

BYO everything, I will provide the area, parking and the bbq, on a good day we could accommodate 20/30 people, on a bad day 15/20 and there is a large council park/playground about 300 meters down the road on the same side, so no need to cross the road, easy to get to via Peninsula Link
Option 4/ Open to ideas but try for under 2.5/4 hours from Melbourne
Some ideas are
Sandy Point Caravan Park (NO open Fires) close to beach
Karingal Scout Camp ( open fires,byo wood,Lyre birds, wombats, close to Walhalla) $10 p/n I think, hot showers, flushing toilets, can be wet, but well grassed sites
Mitchells Crossing (dangerously close to "Speewa's home ground) drop toilets, plenty of room,free, MUST bring firewood, could be very muddy after rain and dangerously close to a couple of wineries
Mount Franklin crater near Daylesford, free? washing water, drop toilets, very sheltered, open fires (byo wood) easy access
So there you go, put your vote/suggestions (no not where I should go) in and we'll see what we can come up with