If you raise resistance to 100% or above with Custom Legendary Mod that race will automatically know they can't damage you and will run for their lives if they are hostile. Most of the versus mutant quests and settlement areas contain mutants at the center of the map(Irish Pride Industries and Everette Estates). The bugs that spawn there should be befriended instead of killed by adding yourself to the bug faction. The electric utility plant next to Irish Pride Industries is a multi-level bug breeding ground nest with a soda machine with respawning Nuka Cola drinks in every variety at the front entrance lobby. So 100% Mutant Slayer resistance total combined armor pieces is what my next Armored Core plus enhancements will be.
Edit: do not build custom settlements within the build area of useful machines like that Nuka Cola assortment respawner for endless soda to drink or sell, visit routinely to check for free soda. It conflicts with the vanilla scripts that respawn items.