sativa or indica?

I am about to start a new grow and my problem is I have a 2'x2' x6' grow area using cfl and bubbleponics to grow, I will grow 5 plants in the cabinet . my problem is I have a white widow and a super skunk clones . If I try to grow both in the cabinet the sativa grows taller than the indica and I only have one 600 watt hps light . if I grow both the sativa will eventually force the light to high for the indica so should I grow all sativa witchwould grow tall and not so bushy or indica wich would grow shorter and bushier also wich would yeld the most in the available space?

if your growing in one container,your really going to have to know your clones,some stretch 3x some just 1x,so with out knowing your stretch and feeding habits,you can be in trouble,if their in separate pots you can elevate on something,as for yied it is hard to say.so many different type WK and skunks.have you grown these before in bubble or even soil.

Just LST the one that stretches.

Like if I had 4 indicas and 1 sativa Id do something like....

X-> <-X
<--O-->
X-> <-X

Where the X are indica and the O is sativa. Lst them so the indica grow one direction and you split the sativa so it grows outward both directions. Or if it really stretch a lot just put it on the end and lst all the way acrtoss.

Or...

X-> <-X
<------O
X-> <-X

yeah.. i am growing two different strains at the moment.. an indica dom, thseeds mk ultra, and a more sativa dom with dna's sour cream.. i just keep the light in the same place, and put stuff under the pots to keep the canopy as even as possible.. its a lil added work, but once you get it down, its not really that hard.. i did end up having to supercrop the sour cream though, and it worked out great..
there are a lot of options for keeping your canopy even, like the above posters said, with some lst, or maybe even scrog would work good for you, or you can just weigh the taller branches down so that they don't grow as tall...
whichever way you go, i wish you the best with your grow, and have some fun with it...

Growing forthegold thanks good advice makes sense