on a trip about 5 years ago we saw some monster GT's around cape richards, we returned 2 years ago and there were none there. it was too rough and windy at the time to target any of the other headlands but i reckon that's your best bet, hit the headlands around the outside of the island, i'd certainly try around that little island off the north east, close to the main island should be a good haunt for GT's. also goold island might be worth a shot. no shortage of headlands to try thats for sure!! good luck i'm jealous!