How do i get the bases to spawn more in the middle of the maps they are only spawn on the edge of the map near the water ?

make sure you're up to date

make sure elevation is 2.5 to 3.5 at most

choose flatter maps, be it procgen or custom.

if they don't have enough flat land then they will spawn on the edge of the map more often as that is the highest concentration of flat land on any map