There i got your solution for the whole large HNM system....

Idea#1 Only a 1 "Free Company" group can kill all of those HNMs during a period of 1 days then it pass on to another "Free Comapny"

Idea#2 Having only 1 "Super Free Company" which will be the only company to take on HNMs, member selection will be done by a SE ranking. (any other ideas?)

Idea#3 HNMs can pop randomly at anytime and anywhere, that will cancel campers and windows.

or make it like exactly like XI, sometime i enjoyed my 30min window break to watch TV or doing something else in RL..