A few of the Kaikoura locals can be pricks about freedom camping…. but I normally find a remote spot and park up 
I own a Toyota surf and I often find enough space to sleep in it…. but I suppose I normally have Kayak gear, Surf Gear and maybe dive gear in there which takes up heaps of room. When I am organized I can sleep stretched out in the back which is quite comfy…. But normally after the second day I have made a complete mess of things so have to sleep on the front seat which is not the best sleepy position when sober, or I could pitch my tent which takes time.