I didn't consider 20/17(2). I can see that the idea behind the play is to prevent Opp from playing 65 64 63 54 53 43 optimally, since he's forced to play one number inside his board (and from splitting with aces and deuces). But the other half of your play, 7/1, is wasteful, which negates the purpose of the play, even when it works.
Me bot says your play would be right if White's outside point was the 11 point (but not if it were the 12 or 10):
Blue to play 33
| White | 84 | ||
|---|---|---|---|
                      | |||
| Blue | 92 | ||
| Position ID: uufBAQBttwUAAw Match ID: cIkNAAAAAAAA | |||