I'd use cool tubes. I'd have the intake and exhaust open to the outside, but isolated from grow area. This way you won't be effecting your CO2 concentration because of your heat mgmt. Then Id use another exhaust line for my grow room air mgmt. If possible Id try to mount ballasts outside grow, but my ballast cords were always pretty short. You can lengthen the cord but you'd maybe want to increase wire gauge if you did.
If the room is well insulated youll need an AC but with this way you're not relying on the AC so much you can drop your energy costs. If you're trying to maintain CO2, then obvi you'd rely more on your AC then your aux exhaust line, but you could tune to your liking.
@Renfro has some good experience with high wattage HID grows, he might have something to add here.