Hmm, very interesting. Seems like a very small space, but for one plant, it may work. I hope you'll keep us posted, I want to see the progress and finished yield. For ventilation, remember the basics. Keep your plant gently moving at least some of the time (all times during daylight is best). Exchange air. Try to keep your light cool. I imagine one tiny fan in and one out somewhere else might do the trick. But try to have the air stream directly blowing over the light somehow on the way out.

The hardest part will be the stealth that you desire. I would not only consider hieght tendencies of the plant, but also potency of scent characteristics. You may be able to design some sort of small carbon scrubber to pass the air flow through. There is a post in the FAQs about how to make your own that might give you some ideas. I'm not sure you can buy anything that small. You are probably aware of this, but when an mj plant flowers it puts off a high level of scent. If you truely want this to be stealthy you must put this high on your priority list. For me to build this, I would think it would be my hardest challenge to do correctly. I guess you'll find out how you did soon after you change the light schedule.

Good luck and keep us posted. I want to see how this progresses. I want to see that computer sitting right out in the middle of the open, where preachers and federal agents consistantly pass by it. Then I'll build one or two.

Maybe you should link to this in the "Challenging growing methods" section. Someone reading there may be interested. It certainly seems like a challange to me.