dude you can fit way more plants than that. i have 3 groLabs and they are by far the superior tents on the market. my flower tent is the gl290 (9.5x9.5), i'm only using a third of the space in there and have 20 strong plants, was planning on 30 but oh well. also have a gl120 (4x4) for mothers, and a gl80L (2.5x5) for clones and vegging. i would look into a couple smaller tents and a large tent if your planning on a perpetual.
if you want the most from each clone, then give them the most. give them adequate veg time, and def two 1000watt lights in an 8x8.....
you can check my journal if you want to see what 20 plants look like in a gl290