If you were to spend 6-8 weeks touring New Zealand in the Spring, (October - November) would you hire a campervan or buy one?

The Mr is quite tall so he would have to be able to sleep comfortably in it, but Im quite small and am the only driver, so I wouldnt want anything big.
Ideally it would be self contained/self certified, so we could freedom camp.

Ive looked at hiring a vehicle from Wellington ( which is where we will initially be based), and the prices are way more expensive than say, Auckland.
Id love to hear any experiences forum members have had, and recommendations too.