I found this great build on You Tube by Tezzer and someone asked him a similar question in the comments and he said he used the lower walls and rotated them the same angle as the roofs. Check out his video, his build is really, really awesome and he used the same structures as in your screen shot for his Stillwaters Retreat.
[url="hhttps://www.youtube.com/watch?v=gGLapcj-ck8ttp://"][/url]