I like to have my lights 18-24in, if you run them closer at higher wattage watch to light burn. What type of strain are you running ? Some have more legs than others and I think we need to factor that along with individual grow space. You and I have similar sq foot and I to don't have the celling height in my tent. If someone asked me to scrog a sativa heavy strain I don't think I would be able to or at least not yield anything worth the time.
This one ended up being highly sativa and she blew right past 20 zips and kept on going. I keep them under 24" from "dirt" to tip of the colas. 3x3' tent, single plant, finished at 200w.
