It would be too easy Iaen. You should at the very least take the Advanced Storage trait; 20% more slots to fill will add some spice. And then, why a single Sphereworld? You ought to find a system with two or three stars, and build as many Sphereworlds as will fit.
The challenge has actually been proposed several times, but nobody succeeded to the best of my knowledge. At least Dogscoff attempted it, and was under way at one point of the game; I do not know about its outcome though.