We rented very small class C campers (diesel) in both countries. Our daughter was with us, so we needed the extra space. When and if we go again, we'd probably rent a camper van, as they're much less to rent, and almost all the campgrounds were very well-equipped. Nice showers, big communal kitchens (some indoors, some outdoors) with (usually) multiple sinks and cooktops, recreation areas, and most everywhere, the "barbie"...flat-top barbeque. In other words, we didn't need a lot of what the class C's contained, except the extra space for our daughter. (Since fall
can be chilly in the south, we did enjoy the diesel heater, though!)
We went in their fall
(our spring), so rates were pretty reasonable, both for the camper rentals and the plane fare. We spent 8 days in New Zealand, camping around the top third of the north island, which was beautiful. Great produce and food, too! We tried so many unusual fruits from the roadside stands.
We spent about three weeks in Australia, renting one-way from Sydney to Cairns. We certainly wish we'd had more time. Here, too, the campgrounds were great. In both countries, we really enjoyed meeting our fellow campers, who were usually locals, Canadians or European. I guess fewer Americans do the camping route there, as most people we met assumed we were Canadian. It seems that camping is really a way of life in New Zealand and Australia, and we never had a hard time finding a place to camp without reservations. I only reserved for our first three nights at the national park outside Sydney, to make sure we'd have a spot in that very popular (and beautiful) place. The park is a short walk to the train station for going into Sydney.
Australia's distances are really long, so I'd really suggest the one-way camper rental, to allow you more time to visit new places. The three-legged air ticket only cost a little more, and was well worth it, especially since we caught a big fare sale with Qantas Air. Even with that, we really had to push to see and do the things we wanted to do (tour beautiful Sydney, take a sailboat ride on the Whitsundays, snorkel at the Great Barrier Reef, and zipline in the rainforest, etc...) We were only able to spend a few days in each area, driving long hours between, as I remember. There's much left for us to explore in both countries, if we ever get the chance again. We'd like to plan on three months next time.
PS Your son was a lucky guy!