With those long floro tubes it's best to keep the plant really short, and flat on top. Your next clones should have bending, Topping or LST done to them so they dont grow tall.
Those floro tubes might be better for side lighting, where the CFLs could be placed right over the cola of the plants, with a reflector. I know you're think this may require a lot of CFls, but even a 13 watt, with a good reflector placed an inch or two away from the cola of the plant can yield impressive results. This requires a few more CFL bulbs, but not necesarily much more watts should you chose to use 13 or 18 watt bulbs. Especially if you keep those floro tubes as side lighting, you will be impressed with how just moving your lights around can effect your yield. If you don't use reflector for your CFLs you're automatically wasting a lot of the light power CFL's have to offer. No matter what you decide, using reflectors will help you double your potential yield.
Hope some of this helps. Feel free to visit my thread if you have any other questions.
https://www.rollitup.org/cfl-growing/199973-cfl-wrap-around-5.html