I would be thinking of taking an Australian manufactured cam-pod, not a copy or sort of clone, the real deal. Best portable camera stand, other than a tripod.
Good luck with the weather, you may find it interesting, to say the least.
Once in the south Island we had water tanks of water coming down, not buckets. We decided that about the only thing we could do was to visit the glow worms at Te Anau, well there was a slight problem, the caves were flooded and the punts couldn't fit under. It was wet, really wet.
I would be taking 400 ASA film myself.