I run 2 600W HPS in flowering. I believe you would be better off with more room. My area is 7ft by 8 ft.... and that does not include the nutrient tank or control bucket in that room. ..its next door in another room.

The one thing not discussed is fresh ventilation. VERY IMPORTANT. 1200W of light produce 3000BTUs of heat. A portable electric heater puts out about that much heat as well. Now picture your little room on a hot summer day and you have an electric heater on full blast! Your plants will not do well if that is not under control. You need fresh air coming into the room, and the hot air needs to be removed.

SN