The Modified Maclean Scale (MMS) level 3 is what has been determined as the highest level allowed in New Zealand for rabbits, even though it can be a sticking point, it is what it is.  All regional councils are meant to monitor to this level with compliance notices going out if deemed over this in to large an area of a property.

The method used to work out rabbit numbers in New Zealand

Full document here:  Modified McLean Scale  along with some thought’s from the NPCA HERE on the MMS.