"Made entirely of crates." Correct me if I'm wrong but I see a light in your first image, how could you lie to us?
Nostalgia, it'll grab you where you're not expecting. . . . What if I made the whole map out of crates . . .
This is a crate idea, but the play space looks a little boxed in. You also might want to look into some possible containerment issues. I'm not sorry for this post.