This is why the NBL should go for a two tier national comp. With the SEABL merging into a division 2 national league.
Run the NBL during summer with big markets and big budgets then run a national version of the SEABL. Then the state comps eg. Premier league, Big V as the division 3.
NBL becomes big market league: Adelaide, Perth, Sydney, Melbourne, Brisbane, NZ and 2 others.
SEABL would change into a division two comp with 2 conferences and 20 teams (10 each conference).
South Conference: 3 WA teams, 2 SA teams, 1 TAS team, 4 Vic Teams.
North Conference: 1 NT team, 5 NSW teams, 4 QLD teams.
Division 3 would be the state leagues, with the remaining teams. Pro/Rel system with div 2 national league.
If one of your states teams places in the bottom two of the conference of div 2 they are relegated and the winner of division 3 (state league) will be promoted to the national league div 2.
E.g. Norwood are in the national comp but finish bottom, and West win the Premier league flag, West then have the choice to enter the div 2 national comp in replacement of Norwood.
This would mean dominating state level teams can take a step forward, whilst the rest can keep on cruising.