Pleased to hear you don't own an overnight pack Vino - these things only slow you down

However, I'm now pretty much resigned to the humbling prospect of doing this as a - dare I say it - overnighter

The quickest access is from the north by flying into Boyd hut. Don't think I'm prepared to lower my self esteem that far down though. You still have to get a permit for access as well that way.
The green route is the quickest by foot. A 3.5 hour walk into Waipakihi hut in the afternoon, followed by a big day following out to the peak and back, with an easy walk back out the next morning would make this a leisurely 3 dayer with travel to & fro included.
There is still always the option of approaching from the south via Thunderbolt & Ecology Stream. This wouldn't require a permit (doesn't cross any private land), but would be a longer & no doubt less pleasant experience.
I can see taking a sickie on an upcoming fine weekend may be in order...