There's a little island a few hundred miles south of Diego Garcia called Tie Amsterdam. Perhaps the folks who live there might be interested in selling the island and moving somewhere else a little less isolated. Buy the island, put the detainees there and air drop the detainees food and water once a month. Find another similar island for any female detainees. Remove all the buildings and anything man made. Make sure there's nothing to communicate with or build a boat out of, remember Thor Heyerdahl. Then let them alone.