Once I have killed all teh defenders, I still have to trog around and boringly kill all the structures.
It’s just tedious.
Just give it a quick message: ‘With everybody dead - you quickly sabotage the structures’ and call it a day. Then we can get back to the game…
I probably would not even bother with the message - just win.
Might be a better solution gamewise to change it to the endless reinforcement mechanic from the lairs since “everyone” is in fact not dead. If your mission objective is to destroy the structures then that should be your focus, get in, do the task, evac. If you putz around focused on something else you have to deal with ever increasing reinforcements as the haven defenders start to rally.