I decided to start looking at accommodation options for the rally today. Gave the park a call as things seemed a little odd ! Some notes :
1. It appears you can't book at the moment through the Big4 website - says nothing is available
2. They have their own website
https://www.kingaroyholidaypark.com.au/ which you can book through
3. For those who will be camping there are a number of options - tent site, unpowered site and powered site. If you like parking your car and/or trailer next to your tent then the tent sites will not work as they do not have vehicle access. They do have grass powered and unpowered sites that would be more suitable
Hope this helps