If they are looking at trialling new rules what about sides having the option of having 8 tackles if they don't kick on the last tackle. They wouldn't be allowed to kick on the 8th. Would add a bit of variety.
A few other minor tweakes:
Any ball kicked dead on the full from outside the 20 leads to a change over from where it was kicked.
Any ball kicked dead from outside the 20 leads to a tap from the 30 metre line.
Any free kick in the defendng 20 can be taken from 10 metres in. At the moment not much advantage getting a penalty on tackle 1 on the sideline in your own red zone.
Like the idea of six again for minor infringements in the play the ball.