I agree with RHCP -perhaps even a 3 point conversion? -Also think if you give away a penalty on the 1st tackle the other team should get 'zero tackle'. -There's a lot of change still needing to be put in place when it comes to reffering.
I think that if a team concedes consecutive penalties (i.e. concedes one, then another one in the set that directly ensues) for ruck infringements / offside - the attacking team should be given a penalty kick for goal AND then receive the ball again from a line dropout. I would also apply this rule to blatantly obvious professional fouls such as the Cronk incident. It would stop the tactic dead in its tracks.
It would give you the chance to score 8 points in a few minutes. Defending teams would very quickly start to question whether it was worth holding down in the play-the-ball that second time, and unlike the 'fear' of the sin-bin (which clearly no longer exists), this might actually cost you on the scoreboard where it really hurts.
You could take the 2 points and the start attacking again from the dropout. If the defending team gave away more penalties you would take another 2 points and start all over again from the dropout.
Imagine if that was the rule when we played the Roosters. I'd love to have seen the Roosters using their ridiculous tactics on the line then.