Nepal got some amazing roads, went there in 2001 in to the mountains, the roads are mad, as for off road opportunities, I doubt there are that many, but the roads they have would be enough. It an amazing country, people are great, I would go back at the drop of a hat if I had time/money.
As for Tibet, it should be possible to get in all the Everest expedition the go from that side drive to their base camp, so it must be possible to get in, but maybe only as part of an organized group.
I think for the next few year I will have to stick to the Alp and Pyrenees, or win lottery
