I say go for it. Guys for some reason never want to give up the garage. They think it is "their" room. If there's not a car in it then they'll make it their workshop or something. One of the ladies at our LQS is buying a new house and is going to to close in her garage and get one of those motel heat/air units. Don't know how much those cost but that would solve both your heat and your air issue.