From my point of view the official CoOp modes are suboptimal designed and unsatisfactory regarding game logic and plausibility. They even earn the golden raspberry award in this regard.
So... the way out could be an own server, however, this only makes sense if the questionable paramaters can be influenced.
Where can I read something about this?
The core of the game is promising but what's going on currently is just not worth the play time.
Edit
I've found snippets like this one but I can't imagine that this is all what's available...