4 for a road trip in a roadster pickup! Sure!

[NZ28ModelA]

There have been times when I wished I could take more than one passenger with me somewhere in the pickup, and short of tying Grandmas rocking chair in the back like Beverly Hillbillies, I was sure it couldn't be done.
We had some rear seats out of a 10str van for cleaning and I jokingly thought what a great photo opportunity!!

But it has started me thinking about the legalities of rear seating in a pickup??

When I was a kid and before seatbelts were compulsory, we used to sit quietly in the back of a ute on the way back from an outing without it being an issue. Can you still do that with a vehicle that never had belts at all? Does anyone transport passengers in the back of a pickup now?

I am unsure of the rules here in NZ, I wonder if i can mount this seat arrangement without an issue, or would i have to go through the whole engineers/certification process? Not that i am too serious about it..

Kindest regards

Steve