It seems when enemy camps spawn at that certain distance to the town, is it then calculated out from the camp standards position or all the structures in the town? My observation says that it is the structures and even the roads?
Had alot of loot in a town a while ago and decided to build a road so the workers could collect it faster, but it seemed to only make the next enemy spawn even further away?
IF the roads count into this, would it then not be better to let those be read by the algorithm as non structures? or how it technically could be done…
I would love to be able to build some more infrastructure on the map, but it seems to have an negative effect in some way at the moment.
If i am missing something, please shout! 
Thanks.