I have never done this but I am a big fan of CFL's as it is really adjustable as you can replace the bulbs and change the height of the light. I use CFL's on small tanks.
Every 20 long journal I see with these lights use 2 of them, on occasion 3. So I would just do two.
I wouldn't worry about trying to improve on the idea, you can eve get straight style ones that screw in but they are had to find in the right spectrum. It works well as is and can be attractive looking with the right reflector choice and no other work. I would just stick to what everyone else has done successfully.