Absolutely without chance. Until council in every city with this naive system starts to fine those who comes before 6pm and does not hesitate to “book” it’s place with QR code, it will never work. Been to Wānaka, Hāwea and now Queenstown and the story is always the same. The page says all places are free and once you get to the spot, the carpark is filled with nearly double number of vehicles which are there from 4 sometimes even 2pm and of course without registration… Don’t even bother trying

Be careful, the rangers patrol all day long. They're already there by 8:15, and by 2:30 PM the parking spaces are already taken. And forget about sleeping outside the parking areas; there are several police officers who think they own the place, and even if you're self-contained or only planning to sleep for two hours, don't even try. They'll fine you $400 without asking if you're inside the parking area or not. In short, leave your car in the morning like everyone else does, and don't rely 100% on the QR code availability.

Part of a normal car park with 10 hour stay, so often non-camper vehicles are parked in campervan bays

Only a few spaces in a small car park a short distance from the airport. It is noisy and dusty due to the current roadworks next door, but adequate for one night. Toilets are about a minute walk away, as is a water fountain. A short distance from the car park there is a McDonalds open 24 hours which is nice and you are also at the lake in 10 minutes.