Motorhome travelling in Oz

Weltonian2

We're flying out to Oz in September to visit family near Brisbane, stopping off in Hong Kong, then to Sydney where we're contemplating hiring a motorhome after a 3 night stay, for 17 days until we fly out again from Brisbane.  Does anyone have any experience
of motorhome hire in Oz/campsites and if so, do you have any advice please? We want to get on with this sooner rather than later to get best prices.