antillies: I know exactly what you mean. Unfortunately, I don't think the AI is moddable, but you may want to check swrebellion.com just to be sure. They're a community of modders for Rebellion so something like that might exist.
Otherwise, I would say giving te AI a head start is probably the only other way. Recently I've been contemplating conquering the majority of the core systems, building them up, and then leaving them denfensiveless and letting the AI have them. Not sure if that would work though.
I tried abandoning my planets in a couple of core sectors in a game as the Rebels. I figured that would let the Empire secure a couple entire sectors, and make it more of a challenge. After 1,000 days of game time, they still hadn't touched my defenseless planet in the Corellian sector, or the two in the Sesswenna Sector. O_o
Oh well... guess it's time to try some multiplayer . :P