Would it be possible to add the mobkill command like every hour or something? Really hard to do the pack when mobs stop spawning due to hitting the limit cap for the server. Since the beginning of the pack is pretty much gated around gunpowder aka loot drops from monsters... having them stop spawning after like 20 mins from the last mob wipe is really annoying. V/R EyeDeeTenTea
There is a chunk limit for how many mobs that can coexist at once. Therefore other mobs on other islands should not interfere with the mobspawning on your island. Could be that your island is located in an ocean biome as that limits mobspawns massively as it's a vanilla mc mechanic.