I'm sort of retired and too lazy to check it myself.. but isn't it possible to make a parallax or what's-it-called background on layers other than 8? If so, I could imagine that it's possible to achieve things like 3-dimensional clouds moving in front of the layer 8 sky.. or something.

While we're already at it, I proudly boast with my use of the 3d background in Fragile Existence. ;o