The nice thing about 1/8 mdf is that it can be curved in the corner. Gatorboard is nice stuff, I use it for other applications though.
mixed media on MDF
I like foreground to have most of the detail when it comes to trees and backdrop to be a bit more muted. The nice thing about painting its easy to paint over it with white and start over. which was done on at least one occasion
this is about 6 inches from track to back of wall