Ok. Two words for ya. Air pots. Thee gallon equivalent and I'm growing 5' monsters. That will cut down on a lot of soil and space. I can grow 10 plants under one 1000w hps. And sence we're talking autos here you can forgo the mh. If you've got that much space why not just do a grow room instead of a tent? Mylar the walls and build a simple partition. Don't forget a charcoal filter and turbine fan, also a GREAT exhaust system. That much light in any space is going to create an oven. Best of wishes, and good luck.