I still remember my first time out there in the 90s when I showed up without reservations for anything (backpacker mentality that I can always find "something"). I went over to the caravan park and they gave me and another backpacker from London a pillow and blanket, and we slept in a covered picnic area (and refused to take any money from me in the morning). A third backpacker that was in tears was able to sleep in the living room area of a couple that had a suite. The next day I got space at the YHA.

Have you looked at shared dorm accomodations there at the YHA? $A32-36 a night. If you're going to be out all day, and just there for a couple days, see if your dates work out. I checked some sample dates in August and they have space. It's right next to the Pioneer Lodge.
http://www.yha.com.au/