Yeah the miliatary road is still open. I wasnt quite clear but when I say 'north moor' I am refering to the half of the moor north of the B3357, which is hardly an accurate description I must admit!
I agree that the area around Yes Tor/Oke Tor is probably best avoided if you dont want to meet people. The northern moor does have some truelly remote spots though. A couple of my favourites are Fur Tor (at the end of Tavy Cleave, with an outstanding view) and Wild Tor, which is also very remote and near to Watern Tor, which is relatively unique as a Tor.
I stick by my assertion that you can camp anywhere because I have always been able to set up a tent within 100m of where I planned. Of course I have never planned on setting up my tent on a hillside or in a bog, but I have yet to find a tor or river that I cant pitch a tent at and have a good nights sleep. So far I have camped at:
Wild Tor, Watern Tor, Bowermans Nose, Hound Tor, Saddle Tor, Rippon Tor, Mel Tor, Great Mis, Grimspound, the west Dart, the walkham, tavy cleave, Sharp Tor above tavy cleave, Ger Tor, Great Links, the beardown man, Grey Wethers, the abandoned farm nr fernworthy, fernworthy woods, Leather Tor nr Burrator, Down Tor (which has a brilliant spot overlooking Burrator) and I think that's it! My walks around some of the southern moor have not brought up much in terms of photographic interest so I have never camped there.
On the subject of water purity, I do drink directly from the streams and occasionally from rivers. I have never been ill but obviously with animals and people about the potential is there!