G'day Greg...not a lot of scope around Narrabri, except for Running Bare,
which may not suit you.
If you look around, you might find some quiet access spots to the Namoi
River. I have done some nude walking on more isolated tracks in Mt. Kaputar
N.P. Occassionally you can get into the Burren Bore, but there are usually
people camping there these days. Some spots along the MacIntyre are worth
checking out if you are up that way. The Pilliga is a vast area with lots
of tracks and you will usually find spots there OK.
Good luck!
Frank Maundrell