Thanks for the reply.
Some more questions if you don't mind:
1) Would alot of the places that you stop for over night be in total darkness? Especially for those areas which are near to the beaches and mountains?
2) Are there seat belts for the seats behind in the cabin? That is something which is probably good if there are more than 2 person and the rest of the people behing would be secured
Dark? Yes, especially at night!!!
If you're stopping outside of the towns it will indeed be very, very dark, especially if there's cloud cover. It sounds to me like you should probably stick with campsites to be honest, you do sound a little nervous about the free camping thing, and you don't want to spoil the holiday. Of couse, one of the best things about camper vans is you can change you iteinary, so if free camping turns out to be not your thing you can book into a site.
We stopped at a lookout down the road from Mt Cook and that was pitch black at night. But when we woke in the morning, the view whilst eating breakfast was simply stunning, much better than staring at tthe side of another camper.
And there were belts in the back of the van we hired, you'll have to check with whoever you book with to make sure though.
Have a good trip.