Ehhh I think if you scrog/lst real good with minimal veg and cool tube a 400 with good ventilation you could be able to get away with it. If you hung the light on the very top and gave the minimum distance you'd want the top of the plant to be from the light, which is about 8 " for a 400 in a cool tube, the max you could grow the plant would be a little over 2 ft or 65 cm (including pot). I've lst d plants under 13" in a 10" tall pot on a 3-4 week veg so I know its possible. You'd just have to be able to completely get rid of the hot air to keep temps in check. That would be the hard part to do stealth. Edit... Cfls or t5s are not bad at all. I use both exclusively and grow the same quality nugs my siblings and friends do with HIDs, Just not as much but its not like I get half of what they do. Usually its within 10 grams with similar veg length and I save money on heat comparatively.