Hey there man, realized no one has commented on your post here so I will try and help you out.

Now since you're going stealth you do not want to attract anyone iwth a big beaming glow of light from the MH/HPS, so I would suggest using 100w CFL's. They're low heat, next best choice to the MH/HPS Ballast IMO.

Now let me know more information, how many plants are you growing?
I would say you could do 1-2 in a rubbermaid container, providing that you LST(Low Stress Training) them to keep the height to a minimum. Also purchase a 100% indica strain, as indica tend to stay the smallest during flower/veg.

Never use tinfoil as a light reflector, use mylar. Mylar is a much better reflectave material.

You can find Low Stress Training guides widely across the internet, simply google Low Stress Training.