Controlled ac is not bad if your profits are not hit because of it however one must be very careful here, most fire hazards happen because of ac and its damage, so if you have many alarms telling you how the room temperature is and have tools to stop if failures.
Good information, great point.
Window A/C miner builds are great for controlling GPU overheating, while maintaining it regularly (a lot of dead bugs can clog it up and cause a fire potentially).
Lets say for example you have a couple blower-fan cards; you can design and construct an elevated enclosed wooden box, trapping cold air in. Create mounts for all your hardware and hole slits for your cards. You can then attach small diameter ducting to each hole and direct it the heat wherever you want; outside with a fan, a fish tank, a near by room, or maybe warming a pot of tea.