I know the QRL and NSWRL have rules about the number of regular season games you have to have played in any of their competitions to be eligible for Finals Football and I've found relevant competition handbook and it looks like the magic number is 8. I imagine TMM and CHT would still meet that mark...
Still remember watching a lower level game - can't recall if it was NSWRL or QRL and think it was a news article on NRL360 or Fox showing how stupid the enforcement of "playing the lower level game" was - where a middle/edge NRL level player walks on to the field with his team, his team kick off and the player immediately trots back off to be replaced by the incumbant player in his position.