There is lots of options, each one giving you more controp, but costs money.. If we had YOUR credit card :) we would make the big room a lung room, and then each 4x4 would have its own fan/filter/temp/rh fan speed controller...
Remember when we go c02, we have our temps about 82*.... so that is a lot easier on the ac, esp if we cool the lung room.. I would run the rh at 60% in the lung room, and have a temp fan controller set to 82 in each 4x4 area, and what ever temp in the lung room to maintain the 82 in the grow chambers... Im guessing prob 76.. Just make sure you got good air flow and good manicuring principals, AND common sense..
So see there is a lot of configurations.. Its just about how much you want to invest..
Right now i would build your 4x8 with divider. Set up with fan/filter/tray/dtw watering system..
Grow these out so you get a lil more used to running a res..
Btw, we aint gonna be mainlining anymore.. Sry
You will be doing basically
SOG= Sea of Green
There is your homework..
Google and read about sea of green technique...