Newnes, have a look at thishttp://www.nationalparks.nsw.gov.au/par ... 51&Type=xo
Ozzy will probably fill you in though as he goes there a lot.
Otherwise there is Glenbrook but not exactly off the beaten track but I have camped there and it was still fun. they have composting toilets, tap water and firewood. And it's good because it's not too far away (well from us anyway)
Let us know if you find any other spots.