Wow... lots of reading to catch up.
Jess... fans as exhuasts is good. I'm with Gypsy, I don't think you need an intake fan... just somewhere for air to come in.
I think your plan should work. Let me know if you want me to draw anything up of what I would do.
And for 4 oz per plant I would say maybe a little taller than 12"... like 14". I mean my hindu skunks with the problems and all, were switched at 14" and the biggest got little under 3 oz. under 650w, and only 400 for the first month flowering. So I'm saying that while it's not garunteed, it shouldn't be too hard to get 4oz from your girls under 1000w.
I think there was more covered but I forget.