I wish... 12' with rafters exposed so there's zero chance of a lift of that size ever being installed. I actually go back and forth about closing off the ceiling and insulating for AC. It's something I'd like to do, but I use that space for light, bulky storage and would feel claustrophobic with the space sealed off.Your idea should work, although for reasons mentioned above, it might not be as simple as it seems.
What is the ceiling height of you shop? Could you use a 4 post lift to store implements off the floor and park the tractor underneath?