Ya, I have the lights on all at the same time, both top & bottom. My cab is 6' h x 3' w x 1.5' d and I gave about 48" to the lower section for the mothers and the top 24" to cloning and early vegging up above. The side lights are T8's 17w ea 6500K.

Here is a link to the building of it: http://boards.cannabis.com/closet-ca...g-cabinet.html

There's no heat problem yet but its winter in so-cal and I have the lights on at night with the windows cracked a few inches. I live just a few blocks from the beach so I have kind of a buffer...its warmer in the winter and cooler in the summer here than it is inland even just a couple miles.

I've only been using this setup since mid December so my experience with how big they can get is limited but I topped the Kush bush you see there and I'm LSTing the small Jedi mother next to it. I still have plenty of room for them to grow more and I'll just keep pruning them.

I think you have plenty of room to have a cloning section in that cab of yours depending on the strains you choose to grow out.

Good luck & happy growing