Eremita, you will most probably get a correct third row from a car or truck wrecker - be aware you vehicle will no longer be considered roadworthy if you alter seating capacity as described on VIN Plate - Have you considered something like milk crates with mattress/cushions on top. Can screw to floor easily and provide space for storage.

Yes, there are many options to make a bed. The thing is that I wanted to be able to carry people also. I was told it could be "certified". I am going to get more information about the certification.

I know some people who did it. But it was too expensive, so I was thinking about getting the seats and paying for the installation only.

Eremita, you could be seriously putting your Greenslip or equivalent at risk in a worst case accident scenario, then "broke "would not describe your pain.

If there was originally a third row of seats and your VIN plate indicates you can carry those extra passengers - you are permitted to replace seats with correct fittings and seat belts - If modifying vehicle, an Engineer's Report is mandated by Vehicle Design Rules (VDR's). If you don't have modifications certified you can be in a lot of trouble, particularly if you are involved in an accident and an injury occurs. Criminal Charges may apply.