Motorhome Camping IN NZ

Check some of these spots

https://www.doc.govt.nz/parks-and-recreation/places-to-stay/stay-at-a-campsite/freedom-camping/

Lots of free camps around NZ

I suggest you get Wikicamps NZ on your phone or tablet for a good guide to campsites, free or not.
The highlight drive for me, and there were many to choose from, was from Te Anau to Milford Sound. Spectacular isn't a good enough word for it. Watch out for the brazen parrots that land on and in your car and start chewing on the rubber bits while you're out taking photos.

Not recently, but on the 3 trips to NZ we used a firm called "wenderkreisen" for our camper hire. Very good rates and service.
There is not much need for joining travel organisations, information is readily available. We free camped all the way, van parks are pretty exy.
Plenty of NP's, free lakeside/riverside spots, more so on the S Island.
Your camper/MH must be self contained.
mike

Not for 30 years, :) but if you join the CMCA (Campervan and Motorhome Club of Australia) here I think they have reciprocal rights in NZ or the equivalent club in NZ, you will find that they have campsites reserved exclusively for members and have access to details of publicly available sites.
It is ESSENTIAL that the motorhome is fully self contained with toilet and grey water tank.
Cheers,
Peter
OKA196 motorhome

We have motor homed NZ South Island twice. The first time we loved it and plenty of Freedom camps to choose from along the way around. The second time was 2 years ago just before Covid shut everybody down. We then got the feeling that Freedom camping was not what NZ really wanted. Now if you price the motorhome daily rates, freedom camping is the way to go but more and more we found they wanted us to use their caravan/motorhome parks. This way increases your daily cost. Another time before, we hired a car and used motels/hotels. This is by far the cheapest way to travel NZ.