Let's talk a little bit about air quality.

The plants don't need fresh air, they need CO2.

Having to keep your temps down and bringing in fresh air can all be solved by going to CO2 and a dehumidifier system.

CO2 lets you run higher temps so you don't need to vent as often. Temps can be controlled by A/C.

The only thing you will have to worry about is humidity. Solved by a dehumidifier or vent fan.

I know, you can't afford all this right away. That's OK. You can add as you grow.

Start with vented hoods and vent them outside the room. I vent into my attic. Then when you can afford CO2, you will only have to hook up the input of the fan to draw air from outside the room.

You need plenty of oscillating fans in your room to keep the air circulated well. The leaves of your plants should be moving at all times.