Oh, you can build the layout in sections of manageable size that attach securely to each other, and you can hang that assemblage from a ceiling. You really can. If you want it bad enough. And it doesn't have to go in circles for that to happen. As for permanency, you didn't say you were buying the garage. When you buy a house, you going to move the falling-down garage to the back yard? You can design a layout so it can form part of a larger layout when you get more space. Eventually you want to go from Point A to Point B, and you'll probably want to go through small stations X and Y. So start by going from X to Y. That will give you a place to start when the time comes to go big. Don't limit yourself, son. You can't always get what you want. But if you try sometimes (and lower your standards, and use some imagination), you just might find you get what you need.