The club can't be involved in sourcing TPAs. In all honestly actual, registered, above board TPAs are more or less meaningless nowadays. The NRL cracked down on them in 2017 and by 2022 the total value of TPAs was about 3% of the cap:
https://www.nrl.com/news/2022/04/29/nrl-unpacked-how-does-the-salary-cap-work/ That would be about $345k per club, total.
Basically, if a club wants to pay its players more than it has cap room it is cheating. Does that happen? Sure, I don't doubt it. But if we've got contracts registered with the NRL that are $750k short of the cap and suddenly sign Payne Haas I suspect the auditors would be at Concord within the hour.