If you're dead set on Fluorescent, you might want to try fitting the fluval power compact 13W driver and bulb from the Flora/Ebi line in there. I would recommend ventilation. One idea is to put a small 40mm computer fan on the back of the nice enclosure you built on the left, and cut some ventilation holes on the back on the right. That would pull air around from the right, over the light and balast, and exhaust it out on the left. It might be a little noisy, but it would work.