He just said he has that temp. If he could drop it that low I'm sure he would. What will lower your temp bro. Is if you seal up your tent, open your windows at the end it'll draw up enough of an air flow, it'll be the temp of your grow room, so however you can cool down your grow room by way of leaving your window in an9ther room open and a window open in your grow room you should be able to keep the temp at room level by doing this. This way you'll be able to use your carbon filter if you need to scrub your air? It all depends. If you domy need to scrub your air then hang it in your tent and just leave your intake fan in your tent with ducting off to circulate your air, as you don't want fans blow directly on your grow. Also you can trim some but leave the bulk of the sugar leafs on your plant, (whole), as it draws sugars in. I've dried 1 plant 3 different ways and the best one was hang dried at 60-65 at 23.5 during the day and around 21c at night. Don't worry to much about hitting 20c. Things like that do help you bud I'm not disagreeing but understanding VPD and how co2 and negative pressure environments all help, but you can get some pretty darn good bud without producing duspernersy grade weed.
Good luck bro
Feel free 2 DM me if you need details, and I'll help if I can, tat is. 🤔