Girraween, sundown and border Ranges national park bush camping

Seeking information on free bush camping within the three listed nation parks. I have seen people say that you can free camp or wild camp aka camp at a non designated camping area legally within these parks but am seeking further information. The qld national parks website for sundown states vaguely that "bush camping is permitted within all areas of the park". but does this mean that I can stray from trails and find a camp? information about girraween national park would be greatly appreciated.

thanks