For what its worth--if you understand the way weather, and more specifically how the wind reacts near mountains, it is no big deal to fly low over mountain tops.
I fly in mountainous terrain, (6,000 to 12,000), working fires for 9 months of the year. The best thing you can do is take some lessons in the mountains with someone who flies them on a regular basis.
Here is the best book that I have found for understanding weather. It is fire orientated but gives you a wealth of knowledge. I refer to it often. For understanding wind in the mountains---I would recommend chapter 6.
Go half way down the page to where it says Reference Material, and open the relevant chapter of the Fire Weather Handbook.
NWCG Fire Training