After my first grow box...I'm building another

I've been vegging for 5 weeks now and the plant is looking good. Thinking of flowering soon but now I want to build another grow box and start a second plant from seed to double my output. The box I've already built has nice lighting, temp control, ventilation, and a carbon filter that I built for it so it is well suited for the more difficult flowering stage. My second box would be relatively easy, just steal another space blanket from work, buy a couple 6500k cfl's for about 6000 lumens for the one plant, an inline fan w/o carbon filter and I'd be good to go. Like, 20% of the effort of the original one and double the output.

Good idea?