I am using a edited file to create a truly insane campaign and see what my computer can really do. 100 factions, 1300 habitable planets, .03 stars tripling the amount of systems, tripled the amount of other celestial objects, and more bonuses for rival AI factions.
MapSizeDefs.xml, <MaxHabitablePlanets>1300</MaxHabitablePlanets>, MaxHabitablePlanets>1300</MaxHabitablePlanets>
Were the commands affecting the star and planet placement I think, this increased the number of stars and planets and reduced range between stars. I used this command to make the cluster map act more like small star clusters separated by large dead areas of space making station and logistics more important in the campaign.
I tried using the command offered Horeemvore, it worked perfectly.
Working on making a cheat map using the rat race mod to see how large of a system i cam make next, should be a fun learning experience modding files.