Psychological torture could help make the gatekeeper more compliant in general. I believe the keyword here is "traumatic bonding."
But again, I'm working from general principles here, e.g. those embodied in the tragedy of group selectionism. I have no reason to expect that "strategies that will get you out of the box" and "strategies that are not morally repugnant" have a large intersection. It seems much more plausible to me that most effective strategies will look like the analogue of cannibalizing other people's daughters than the analogue of restrained breeding.
Update 2013-09-05.
I have since played two more AI box experiments after this one, winning both.
Update 2013-12-30:
I have lost two more AI box experiments, and won two more. Current Record is 3 Wins, 3 Losses.