Crawl Space Grow

I'm thinking of using my crawl space for a grow room. I've done a closet grow before but this will be stealthier because there's no way anybody could ever see it. I'm thinking of building a 3x6 tent down there. I only have 4 feet of clearance though. I have grown in 5 gallon buckets in the past with my 150 hps but I had head room and little floor area. Now I'm in a new place and have the opposite. I think I'm going to use cfl because they're supposedly the most energy efficient and put out low heat. That was my biggest downfall on the last one. Nothing fancy for grow media. Black soil with pearlite in 3 gallon buckets probably to save height. Drip irrigation system with timer for watering. 15 minutes every 2 hours. (http://www.harborfreight.com/irrigation-drip-kit-46095.html) and (http://www.harborfreight.com/two-hour-water-timer-96518.html) Liquid feed diluted and put in 1 liter bottles. (http://www.harborfreight.com/6-piece-watering-cone-set-93182.html) I can't think of any big setbacks I might come across but I don't have the experience most of you do. My ladies in my old apartment grew to about 5 feet with the bucket included so I think that might end up being an issue. I think I could build a planter box in the dirt floor and take that space out but I wouldn't be able to move the plants. Financially the lights are going to cost the most. I figure $10 a square foot if I use 40W bulbs in ceramic sockets. 18 foot/squared total. I have a couple computer fans to use for ventilation. One for inlet and 2 for exhaust. All input is appreciated. Thanks.

CFL is never better for growing. I doubt the energy efficient thing makes a difference when talking 150w.

as far as the height issue that is really determined by when you put them into flowering from veg. You can also use tie to plant down (LST), or you can top/fim your plants to keep em shorter. CFL have to be kept at least 2 inches if not closer to the plant for them to be effective. So the bigger your plants the more lights you are going to need. The lumens die off by half after 2-3 inches, even more further from the plant.

I was planning on mounting them all on a sheet of plywood so I can adjust the height right down on top of the plants. I have a discount at a local lumber yard so I can get the sockets and bulbs at a discount. I was just going to use more of them. Also, how many plants could I fit in a 3x6 area while letting them have room to became big beautiful ladies? I'm aiming for quality. Quantity will come with the outdoor grows when that time comes.