I have never used tbird finish..Could you heat the shop up to 70-75 degrees, turn exaust fan on turn off heater, spray bow, turn heater back on? I am in Florida so I'm not a cold weather expert..but that's what I do when it's below 65 here. I have a small potable ceramic heater in my spray room and an insulated shop. I know it would be hard heating the cold air coming in