Another good idea is to organize an International Driving Permit before departure. It is recognized by most countries and I imagine having one makes life a lot easier when asked to produce a license. I have heard it is a requirement for car rentals but it also acts as an additional form of ID besides your passport.
It is a simple matter of either applying online or finding the nearest NRMA or similar AAA member if not in NSW.
You will need a copy of your current Australian Drivers License and a recent passport photo. The cost is currently A$39.