It's a possible project, but you would need to not only have something that opened and closed, you would need a fan system to drive the air, and you would need to have it be thermally insulated when closed, and unless you have a very conservative cooling algorithm you would probably want a heating system to deal with the room getting too cold because the room itself is not thermally sealed.
It ends up being a DIY air conditioner/heater, which I'd rather just buy.
If the goal is just to maintain a temperature I don't think you need to go to most of the lengths you mentioned. You have a window that is currently adequately insulated when shut. This is intended for maintenance so no need for a fan to speed things up. However the room is getting too hot now will suffice to heat it back up if needed, but again being slow means it shouldn't overshoot badly either.
It still may not be worth your time, but if just cracking a window would be sufficient cooling for most of the year it could be.