I love the idea but when I have dreamed about doing exactly that in the past, I always worry about the limited field of view shooting out a window and having someone walk by when I was shooting. Have you thought bout leaving the garage door there and just opening it up when you want to shoot? They are doing amazing things with air curtains that keep the cold out. Of course you would have to shoot through it or have the barrel stick though it. Just my thoughts but I would love to have the place to do what you are going to do.