OK, hers how the universe REALLY works (In FL, anyways). Imagine a giant ball. Now, the INSIDE of the ball is textured. Youre ship is in the EXACT middle of the ball. Thats the universe for ya. Interesting, no?
So, YES, you can customly do system backgrounds. Heck, I could do even THOSE in the same fashion as Ship Skins (I'm 90% shure on this). Interesting idea to try...