so each section is like 4' tall right so subtract 1' for pots and 1' for light and your right you do need some small plants. How about some auto plants, Low Ryder 2 maybe, I have heard great things about auto ak47 how about that?
And if you do go with the autosyou could harvest every month or so with the 2 compartments, no mother plants and no messing with cloning. Thats the route i'm heading for now. But if you do go with and auto variety be sure to do a seed run first time through, that is allow the males to pollinate the female buds for more seeds, that way you only have to buy em once.
Good Luck
P@ssw0rd