Dave, on NZ your itinerary (26,123 miles according to Great Circle Mapper) = 41,796km, x 1.25 business class bonus = 52,246 AirPoints/status km. This means you'll get silver and will be only 7500km from gold. Is there any way you can add in some extra legs to use a bit more of your 29,000 mile limit? Perhaps an intra-European round trip?
If you already have a few NZ status km for the year, perhaps this will be enough to push you up to Gold anyway? Star status isn't really worth anything much until you get up to Gold status, IMHO.