Took the JF Arrow for a flight to the longest paved runway in the world. Fully leaned out before I even got to FL185.
On the way south, I was following some valleys, and noticed they were boxing in. I then remembered the CFIT videos I have watched. Observing that on one side of the valley I was descending, I moved across to the other side to catch the updraft, and my -300fpm descent turned into +500fpm to +1000fpm climb. The updraft carried me up the slope, and over the mountains. I then kept to the left side of any south facing valley and it eventually carried me up to FL185.
Thank you Captain Warren Vanderburgh.