By the way I followed the Long Paddock, since I drove between White Cliffs and Melbourne through Wilcania, Ivanhoe and Hay, the road is nice, but it's flat terrain (not much to see), and between Ivanhoe and Hay, there were a lot of flooded parts adjacent to the road, so short of walking on the road itself I'm not sure how you could organize a hike there. The Darling River Run is probably a safer bet. There's a brochure for the river run at the Broken Hill Information Centre, maybe you can ask them for it, otherwise have a look here :
http://www.exploroz.com/TrekNotes/Outba ... r_Run.aspx .
The problem with NSW is that their National Parks service isn't as developed as its Victorian counterpart. On the Victorian website, you have a fact-sheet for every national park, and even every state park, listing flora/fauna, walks, maps etc... In NSW, you're lucky when there's one, and even when there is, it's usually pretty well hidden on their website (the Mutawintji one for example :
http://www.environment.nsw.gov.au/resou ... tjiMap.pdf ).
Hmm now that I have the Mutawintji map under my eyes again, I think you could probably do a one way hike between the Old Coach Road Drive carpark (n°8 on the map) and Mutawintji Gorge (n°6). I think it would be about 15 km one way, and then you could walk back on the road. You would need good navigation skills, as there are no tracks here, and would need to clear you itinerary with the ranger, as the Historical Site is off limits. You should also inquire about any river crossing, and if some ranges are passable or not (they aren't very high so it should be ok though). Good luck.
To get there, a 2WD is enough from Broken Hill, but from Mutawintji to White Cliffs, it's a very corrugated road, it took me and my friends 3 hours to do this part with our van...
Here are a couple of photos :