I just came across a new travelogue of a guy describing his 7 days into Mustang without a permit. He's just done it and its an enjoyable read. - Im quite envious that's for sure! It's good that he added the info of what the penalty would have been had they'd been caught, otherwise a stampede of trekkers might have followed.
Here is the link for anyone interested.

http://www.travelpod.com/travel-blog...5720/tpod.html