I haven't put a lot of thought into this but we could always introduce a 'marquee' style player allowance but call it something else.
Apply some conditions which prevent leveraging from one game to another, promote fair use and stick it to Rah Rah.
For instance, you could provide an off cap allowance of X amount toward a current ARU/NZ Rugby/SARU registered player who has not held a professional Rugby League contract or otherwise played professional rugby league (ESL, NRL, French RL etc).
The player must hold a current RU contract or otherwise be in a position to negotiate a new contract with their current team or organisation. Any players who weren't picked up on a new RU contract, without a contract within their organisation or they've played professional league before, don't qualify for the allowance.
Although, I would rather we promote our own. Plenty of good young kids looking for a shot.