Enemy deployment is very poor in the game , I fully agree
I have read your post and those are interesting ideas, but it is complicated, devs will want easy implementations for haven defense,
and about scavenging sites, it is a lot of work to the overloaded roadmap I am afraid,
and those missions after next patch(fixed bug) with continous reinforcements will be hard enough,
and after mid game there are Acid Chirons, Sirens, a lot of nasty/tricky enemies