How will the bus get on flying in out of of RO?
I think getting in will be more of a problem than getting out.
Runway has been lengthened to the south but this really only helps for landing to the south and departure to the north due to terrain to the south of the airfield. It's a narrow runway as well, what are the wet crosswind limits for the A320? Most bad weather arrivals will be towards the north.
I predict a few diversions to NZAA unless they have arrangements at NZHN for border control.
The fog at NZHN will be less of a problem for departures than the weather at NZRO will be for arrivals.