We always use DoC camps have a pop up camper and awning and are fully contained have our own water,toilet,gas fridge,cooker,shower etc.
Have camped at most DoC camp sites very cheap and most have beach boundary.There is a camp site at the start of the straight before Pikowai it's between the railway lines and the beach they have an honesty box system only $5-00 per night I think that's per vehical only draw back is that you must be self contained.It is owned by Kiwirail.