I completed the backdrop painting by painting a small section in the center to look like a small community's streets and some homes or factories. I also painted the clouds. I am not 100% happy with those yet, but it'll do for now.
I've also been putting a lot of debris, rocks, leaves, ground foam, and small sticks down on the forest floor on the scenery base between the backdrop and the track. The edges of the outcroppings were dry-brushed with white acrylic paint to make them look more like rocks. I also sprayed everything down with India ink and alcohol mixture. Finally the whole area was dowsed in white glue thinned down with water (50/50) to try to keep everything in place. A lot of this area will be covered with trees, but I wanted to have a finished forest floor before working on the trees later.