Why would you want to spend any time at all on the lee side of a mountain? That's fine if you and the winds are light. If they're anything above 30kts, you should stay well away from the lee side and make your approach at maybe 90 degrees to the wind, in a nice low power shallow approach giving yourself a nice big escape route into wind and down the hill.
I have spent many hours taking a max gross weight (external load) helicopter to mountain tops in VERY windy conditions. There is sometimes no way you would even GET to the top of the mountain, without climbing with the updrafts. The last thing you want to do, is get on the wrong side of a mountain, they are much harder than you
