If I was Steve Tew.
My suggestion to get Japan into a competition.
Create a Pcific Rim Cup.
8 nations: NZ, Aus, Japan, Canada, USA, Fiji, Samoa, Tonga.
2 pools of 4, = 3 games each. Then a final.
Home and away structure, sort of, 2 home & 1 away or vice versa. (Then a grand final).
Draw should be random rather than seeded so there is a chance nz and Aus are in same pool.
Schedule this in the November international window (3 weeks), with either first round or final outside the window.
But, is a 4 yearly event (baby steps).
Voila. You have brought Japan and growing USA market into 'our' sphere.
It means NZ and Aus opt out of the NH November tours once every 4 years. This might have repercussions, seeing as it is reciprocal and all that ...... but seeing as there are 6 of 'them' wanting incoming tours from 4 of 'us' I think fall out will be minimal for the SH 'powers'.
Seeing as they've just approved a future 'global calender' I think, this can't be done for about 5 years.
So Steve, copy & paste this and hand it over to your successor to action in 2023 or whenever. This advice has been provided free of charge.