For a 300 sq ft workshop that you'd not want to add humidity into directly with a swamp cooler, what if you made instead a 4" false ceiling of 2x4's on end, covered with thin plastic sheeting of minimal r-value, to blow cooler evaporative air through a serpentine baffle configuration to achieve even contact all along the whole ceiling and plastic. How effective might that be if that evaporative swamp cooler outside was blowing 70F air into that 4" false ceiling space of 300 sq ft when ceiling air temp inside, just under that plastic, before you turned it on, was 90F? Let's assume here no heat gain/loss from above the original ceiling, the top of the false ceiling. Would this setup likely draw much of that 90F ceiling heat off with 1000 cfm evaporative cooler blower 70F? Any guess what the BTU's cooling total range might be for that 300 sq ft with this setup? Whatever its effectiveness, would it likely work better just to let hotter air naturally accumulate up at ceiling for largest Delta T, or use some fans to agitate it along underside of ceiling plastic sheeting, even though that might introduce some cooler air from below, lowering Delta T at plastic surface? Thanks for any thoughts.