The airport at Daly Waters in the NT is a good free camping and observing spot.
I observed M81 and M82 from there last year. We camped near the hanger and there was no one around, just some roos.
The latitude is 16.3 degrees south and the altitude is 210m . It is 590 km south of Darwin and 405 km north of Tennant Creek.
http://www.dalywaterspub.com/
A Google image is attached.