Kaiaua NZMCA park is a campground at 20A Kaiaua Rd in the Firth of Thames settlement of Kaiaua, Franklin, an easy drive south-east of Auckland, and it holds a 4.7 Google rating. It sits within the New Zealand Motor Caravan Association's network of parks, which are geared to members travelling in self-contained campervans and motorhomes.
Parks of this kind trade extensive facilities for simple, well-placed sites, so the expectation is that your vehicle carries its own toilet, water and waste systems, and the stop works as a quiet overnight base rather than a resort. What makes this stretch of coast worth stopping for is the shore itself: big tides, seabirds, the shorebird hides at nearby Miranda and the village's fish and chips. Summer weekends and holidays fill coastal sites first, so planning ahead pays.
For members on the coast road between Auckland and Thames, a 4.7-rated overnight spot at Kaiaua is about as handy as it gets.