I cant see how it would be that hard considering Rugby League and Union are allready playing expanded competitions on both sides of the Tasman.
2 New Zealand sides
North Island
&
South Island
Join the Australian domestic competition.
Advantages for New Zealand
More competition to get into one of the 2 domestic teams rather than the current 8-10 domestic teams.
Better opposition , more often.
More varied pitches and conditions will be experienced.
Advantages for Australia
Increased competition
New group of players and conditions will be encountered
For most teams flying to NZ would be cheaper and quicker than flying to Perth.