I'd say as long as you can keep the door open and have a fan blowing on the plants then you'll be fine. I actually did this with my 400w hps... I had 1 plant in a 22.5in x 22.5in. x 67.5in. closet and used a huge axial fan to blow directly on the plant (and it pushed all the hot air out of the grow space).

Only thing is... when it comes time to turn the lights off, you'll have to somehow make sure the plant have total darkness. If you have to close your cabinet to do this, you better make sure to open it in the morning, otherwise those things might get cooked.

Look into Scrog... it'll help you get the most out of your space (and height restrictions) :thumbsup: