If you really want to cool then think like a grower. Mini ductless AC unit and inline ducting for intake and exhaust. Use an environmental control and when temps go higher than ducting can handle they shut off and mini split system kicks in. The inline venting alone can do the job minus those really hot days. I highly recommend the Panasonic whisperline duct fans. Do the math, get the right size, x 2 since you want intake and exhaust unless you have passive intake like an open door to suck air in from.
You can find lots of growers on craigslist selling equipment all the time.
You are talking closet scale equipment. He's got the equivalent of a 20-lamp grow in 800 square feet, not sure of the shape, and 20ft ceilings.
I worked on a 16x1000w op in about 2000ft^2 and we kept temps below 80 with a 5-ton AC and 2 12" CanFans (good brand, but un-throttlable) and two 10" centrifugal fans in and out (with a fair amount of filtration resistance). We upped it to 20 lamps and it started running about 85, just over the capacity of the AC. The power bill was phenomenal, and 2/3rds of the room was on 12/12. Goddamn that place made some money. Puts bitcoin at $30 to shame. Then the sheriffs came and cut down all our children and ended up dismissing the charges after doing about a hundred grand in damage. Good ole' fuckin' amuuurica.