If I can't get wired broadband I might try getting 3/4G with hi gain Antennas.
Do the NZ carriers do multi in multi out (MIMO)? I assume they need to be at 45 and 135 degrees? What should the vertical and horizontal separation be? I could make it many meters if need be. If there is a number I assume it is related to the wavelength although how I'd measure/rig that accurately I have no idea.