I believe that Australian Football needs to go this way instead with it's rules regarding physical contact....
1. No push in the back at all, ever. Marking or tackling contests.
2. Can tackle below the knees.
3. Can shirt-front and take people out 5 meters within the ball in a shepherd.
4. In marking contests, players taking a mark can be hit (shirt-fronted etc) as long as they're in the act of catching it, where the ball is approx 5 meters in range. Think NFL when Wide Receivers attempt to catch the ball.
5. No 'incidental' head-high infractions. Meaning, if a hand comes up and wraps someone around the shoulders or slaps him across the neck.
6. If you duck into a tackle or bump, it's your bad luck.
7. Revision around the 'holding the ball' or 'incorrect disposal rule'.....basically, if you get tackled and drop the ball it's play-on, even if you incorrectly dispose of it as long as you're making a proper attempt via handpass or kick. However, the emphasis is on being tackled to the ground or pinned around the arms or fall over the ball dragging it in. So, if you get tackled and brought to the ground, without having released the ball, then it is a Free-Kick. If you get pinned around the arms in possession, whereby the ball gets trapped into you, but you haven't been brought to the ground, just held up long enough, perhaps even in a gang-tackle/hug then it is Free-Kick, even if you had no prior ability. If you dive on the ball on the ground and hold it in, a Free-Kick is awarded. Think Rugby Union kind of, where a tackle means immediate release of the ball. The incentive being if you tackle someone, they have to immediately release the ball giving the advantage to your team being able to take possession of it. Due to the huge open spaces of Australian Football, and the difficulty in actually being able to tackle someone with 360 degrees of freedom, then a lot of leeway must be given to allow for more physicality. The only way to create more physicality is by making the playing field smaller to congest it, (which isn't good), or by giving players more freedom (or less rules) to make contact and hard like Ice Hockey up to a certain threshold that outlaws sniping, or forceful head-high tackling etc.