Where about's in Adelaide and what's the budget? Is he coming here as a student or for work? How long's he intend staying in Adelaide?
I don't think any of the metropolitan caravan parks are accepting "long-term" stays any more and besides they'd be charging $20-$30 a night and the total cost would probably be more expensive than shared accommodation. Have you had a look on Gumtree (Real Estate >> share house)?