Garage door opener as a lift for a camper shell

The first problem that comes to mind is the nature of a garage door opener. It's basically a toggle switch. Either on or off, unlike like a variable speed motor where you have control. With my old swing-up door and Craftsman opener, there's been more than a few times where the remote didn't respond quick enough and the door hit what was in the way. Unless you can control the speed, there could be problems. Otherwise, cool idea. Good luck.