We used to have a system that areas of a manageable size for the volume of chatter had a discrete frequency. Everybody that was flying in what is now Class G was on the same frequency, you didn't have to guess what the most appropriate one was.
To further enhance safety, the frequency was monitored and useful operational information (traffic, estimated crossing times, WX etc) was passed on. Those that monitored the frequency even told you when to change to the next frequency and accepted position reports and SARTIME details from VFR aircraft.
Given the lack of radar coverage it was a great system. Now ADSB provides an opportunity to provide similar services at lower cost (if Australia had adopted the US standard).
In summery, draw some lines on a Class G map, give the box a frequency and everybody in the box monitor it and broadcast when required. Simple.