There its already an "Ai" Island, is the one in the upper right corner of the map called the Suhrenfeld Array. This is where all the big Ai spawns will occur, right now it spawns between 8 - 24 Ai, meaning a big battle will occur. Here is a video for the island fight
You can turn the all the other Ai off completely if you like by editing the file dayz_server\DZAI\init\world_map_configs\world_napf.sqf. You would want to remove all of the markers in the file except the ones on Suhrenfeld and Pfeffikon. As an alternative, you can edit the line in this file that contains the spawns, I listed that below.
sample
[8,24,850,thisTrigger,[],3,1]
meaning
[Minimum spawn amount, Maximum spawn amount, radius to spawn in, thisTrigger, [], Ai Level, How many patrols]
["{isPlayer _x} count thisList > 0;", "nul = [8,24,850,thisTrigger,[],3,1] call fnc_spawnBandits;", "nul = [thisTrigger] spawn fnc_despawnBandits;"];