I would hope just a handful of systems would be enough for this kind of mod... I quite like the idea of managing to target and talk to other vessels out of visual range before closing in to engage in PvP combat or to trade.
Another way I thought of doing this mod was to have a system for each planet, so you would really get a sense of flying thousands of miles above the surface, there would also be use of features like gas clouds and flying through the atmosphere would be emulated by a gas cloud layer over the surface of the huge planet, you could then approach lower/closer to engage a docking sequence...