Except the walk from the BOQ on North Island to the main gate for a taxi or the bus stop/ ferry that took 30-40 mins. get a rental car, its cheap and if you dont need it or are drinking, dont use it, have a few middies all chip in for a week and youre good to go.
hopefully SD rental rates are better than at some of the more remote areas. I paid nearly $250 for a weekend rental of a Herz car at Lemoore