In Civ 5 you can't build two cities near 4 tiles, is it possible to increase this limit to 8?

E.g. You can't build two cities within 8 or less tiles between.

I feel in late game the continent map is so crowded with sooooo many cities, I think making cities more sparse would be more fun for me. After city area expansion max out, there would still be a gap between cities where you can pass through to hit players you don't like.