Damn, this is going slowly. But at least I'm close to the finish line.
Here's a new skybox that I just finished also thanks to the help I got here in the forums:
KashyyykThe Wookiee homeworld of Kashyyyk is overgrown with giant kilometer high trees and the Wookiees build their cities and villages high up among the branches.
Ingame one sadly doesn't see much of that "sky" but nevertheless, here are some screenshots: