NZTA allows a max width of 11 m, so 8m is no problem. The tri would sit on a standard low loader with a cradle. Need all the relevant permits, pilot vehicles, permissible routes etc but nothing that has not been done 000's times before.
I am sure Pete at Boat Haulage would have all the answers, and similarly any of the house movers. I know of a 14m x 7m cat moved from the back of Hunua to Maraetai by a house mover without a problem.