Like if your characters insanity gets high enough from murdering mutants then you can start taking the body parts that you collect (Heads, arms, legs, etc..) and then hang them on a pole outside your camp as a way to send a message and ward off off all the other mutants..
The shit will work for a few days/nights but as time goes on they start getting braver and more aggressive so you just gotta keep moving around and finding ways to survive around them while trying to gather up the key stuff you need to get off their island.