Success! Turns out when the New Zealand weather forecast says "mostly cloudy", that equates to "amazing sunny day" in UK language.
Coupled with almost no wind, no snow, and an excellent track, it was a lovely summit to do. I took the slightly lazy option of the Skyline Gondola up to 800m, figuring that doing the next 1000m vertical ascent by foot was definitely enough to count as fair. It also provides some nice photo opportunities over Queenstown!
From there, the path to the saddle at 1300m ASL is easy walking; above the saddle it gets a little steeper and there's just one or two points where you might use a hand to steady yourself, but nothing too scary.
After the obligatory photo stop at the very summit, I set up a few meters downhill and out of the way of others visiting the top:
No problems qualifying on 20m, with thanks to: N4EX, ZL1BYZ, VK5CZ, VK4TJ, VK2IO, VK3KAI, VK7CW all of whom popped up in short order after the RBN spot happened.
I would've hung around longer, but it turned out there was one risk I hand't considered: the Kea. These large parrots took a rather keen interest in my Iridium tracker, and my rucksack now has an extra hole in it as a result! Certainly a first for my SOTA activations...
Anyway, time to go before anything got misappropriated . A quick descent back to the gondola, and a short walk back to the campsite from there.
Will shout if I get chance to do another summit - it'd be nice to do one of the North Island ones to tick off that association as well, so thanks for the suggestions above.