I'm playing 13/7. It give you 5s, 6s, and 44 to make a 5-prime. Because your opponent has the cube, your residual equity as he tries to come home if things go poorly is much less powerful because you will get doubled out of a fair bit of equity pretty frequently. You're going to have to win this by containing this last guy, so just go for the 5-prime. Let's not forget, also, that he still has 24 outside pips (plus the guy in the air), so if you luck into a closeout, you have something like 40% gammons.
I would go with the simple 15/9. Any seven makes the 2 point, 6-2 makes the bar point, and it minimizes shots. I think black's chances of winning are good enough that risks don't need to be taken at this point. I don't think black's chances are so good that extra aggression trying for gammons is advisable.