Actual Sites: Airports adds 600 real runway locations.
These locations are defined as "Large Airports" from GIS data in the public domain. Each of those little gray boxes on the map is a runway you can launch from and fly to to. No need to switch KSC, you can fly amongst any number of landing strips.
Adding all these showed no noticeable affect on performance on my machine.
The dataset I used to build this project does not include number of runways or their or