Venture 5th wheelers are registered as a “caravan/trailer” just like any other caravan. The costs for registration vary from state to state. Registering in some states such as NSW incur stamp duty.
Many companies offer insurance for our 5th wheelers including the CMCA club (www.cmca.net.au) who offer a combined vehicle/5h wheeler package, and RACQ. If you have other cover through an insurance company, they can normally offer you a good deal to cover your 5th wheeler too. Prices vary and are normally under $800 per year.
CTP insurance (compulsory third party) is not required, just like a caravan, as the CTP of your vehicle covers the 5th wheeler too.
Spare parts are available from most caravan supply shops. Other general maintenance is comparable to normal caravans.