Ok, here's my revised idea.
Take the result of the last NRL Premiership match each team played against each other.
Knockout by top 8 sides over 4 weeks to determine winner.
So it would mean 3 extra games for the two sides that reach the final, which isn't that big a deal.
Current Ladder under this format is
1 - CAN - 11 wins, 3 losses - 22 Pts, +134
2 - CRO - 10 wins, 1 draw, 3 losses - 21 Pts, +71
3 - MEL - 10 wins, 4 losses, 20 Pts, +128
4 - BRI - 9 wins, 5 losses, 18 Pts, +118
5 - GCT - 8 wins, 1 draw, 5 losses, 17 Pts, +41
6 - NQL - 8 wins, 6 losses, 16 Pts, +59
7 - WST - 8 wins, 6 losses, 16 Pts, +19
8 - CBY - 8 wins, 6 losses, 16 Pts, 0
9 - PEN - 7 wins, 7 losses, 14 Pts, +61
10 - WAR - 7 wins, 7 losses, 14 Pts, -17
11 - SYD - 5 wins, 9 losses, 10 Pts, +13
12 - MAN - 5 wins, 9 losses, 10 Pts, -48
13 - PAR - 5 wins, 8 losses, 10 Pts, -76 *(Still have a game to play this weekend)
14 - SGI - 5 wins, 8 losses, 10 Pts, -98 *(Still have a game to play this weekend)
15 - SOU - 4 wins, 10 losses, 8 Pts, -66
16 - NEW - 0 wins, 14 losses, 0 Pts, -339
So in the knockout
Week 1
A - 1 v 8
B - 3 v 6
C - 4 v 5
D - 2 v 7
Week 2
E - Winner A v Winner B
F - Winner C v Winner D
Week 3
G - Winner E v Winner F