I'd like to correct something that I said. It's Arjan's Ultra Haze #2 that'll stay small.
Regarding the SSH, I'd have some 3 feet prepared for the girl just in case she'll want to get tall.
I just talked this thru with a fellow pot head and grower that tried this (sativas 12/12 from seed). Apparently you should try a sativa strain that is stabilized, of an F1 generation, so neither SSH or AUH#2 will be the perfect pick. Even so, he says, you could have some bad luck and grow a sativa that just wants to grow like crazy. He's tried this many times. The best solution, says my dude, is to prune your plant is such a way as to keep her from gaining height, but grow nice and bushy. I'm not sure on the pruning part because we were already stoned at this point in the conversation.