I guess you don't get exp for killing pirates and animals? So the players on my server have taken to walling off mobs and not wasting ammo on them. There's no reason to kill mobs. If you clear the objectives in a camp you get the exp event without killing.
I guess A+ for creativeness, but this cannot be what you intended when you created the game. Every camp now is a mess of grass fences, walls and stairs so our players can pop in and get stuff from chests they shouldn't have access to yet.
I get you want to pace progression to content, but there's no reason to kill the bad guys unless they're carrying something you need. Later on when you have more resources, its easy to justify skip killing mobs when you've already got boxes full of weapons and resources.