I have a cab with simular if not the same dementions and have used 6X23W 6500K CFL's on a 2X4 board. It worked fine and the plants get tite nodes and internodle branches. I think that I have fit up to15 plants from seed up to 3 weeks, and right now I have 9 6 in rooted clones and 12 seedlings and a mother crammed in there.
Adieu