Picking up a camper straight from the Christchurch lot is the best way to kick off a South Island tiki tour, the freedom camping spots around the Mackenzie Country are absolutely epic and you wake up right next to the lakes. Most travellers lock in a deal to rent a car in New Zealand way before they land, grabbing a self-contained van with a proper loo and shower so the rangers do not slap you with a fine at the overnight stops. You can check out the campervans and utes up for grabs right here
https://getrentacar.com/en-US/new-zealand .