I'm from Perth, and will be driving there on Tuesday. From Perth, it takes two days of driving (about 11.5 hours each day without breaks).
If you're lucky enough to get a place to stay near the airport, than a car isn't THAT necessary. I'm planning on buying a bicycle when I get up there. Additionally, there are so many pilots up there that borrowing a car wouldn't seem out of the realms of possiblity.
Anyway, something for you to think about....