On our servers we prefer the admins to die when disconnected and not sleep under the map, instead of editing the plugin each update, can you add to the config the value for being teleported under the map, You use -5f, I use -4500f as this kills the admin and their bag.

player.transform.position = new Vector3(player.transform.position.x, terrainY - 4500f, player.transform.position.z);