You don't need to do any custom image creation to make the extra systems. Just edit some text files. Another possibility, I guess, would be to split the Sol system up into different 'virtual' areas. Put Uranus/Neptune/Pluto waaaay out in their own location. But then you'd have a system with no star.
(Hmm, I wonder if you could create a custom background to add a larger than usual star in one direction?)