Just keep the red card for thuggery (eye gouging and other grub acts) and some other colour (fuckit, Blue card) for head contact in tackles/rucks etc. Specific card for the accidental head contact that they want to reduce. Have that at 20mins, and if the players technique doesn't improve bump it up to 30mins the next year.
Leaves the onus on the coaches and players to solve the issue, doesn't ruin the game for the fans, has actions to protect the players and address the hilarious NH opinion that 20min red cards will have players running around like the love child of Richard Loe and Troy Flavell.
















