Not impossible, in fact it would work great for a national chain. You move an trusted area assistant manager(s) into the position temporarily. The position is filed and the chain can "test drive" these assistants to see how well they'll get along in the position and whether they can move up someday. It's the same as running a school for managers, and they'll have a pool of qualified assistants.
Yeah, it would work great for a national chain but I'm talking about someone who owns one small business. ;-)
MM