If you're using fluoros then it would be best to keep the plants small like just have one main bud each and flower the plants very early. Fluorescent light does not penetrate foliage very well at all so it would be a waste of time growing bigger plants. If your grow area is 3 feet x 1 and a half feet then you could have 18 plants (3 rows of 6 plants), with each plant having a 6 inch square to grow in. You would have a single canopy of buds which you could keep the fluoros very close to; you'd have to make sure they were all the same height (all clones from the same plant).
Have you got a mother plant from which to take clones from?