x2 on patterns. Things can be different. In my experience (and this duplicates above entries), there are some items which are essential, and can't hurt to have on hand in addition to what was mentioned above:
1: Quoting Hank Hill, "propane and propane accessories." It would be nice to have propane and someone DOT certified to fill it, as well as a cage of 20# cylinders to exchange. It can't hurt to have some new 30# cylinders for sale as well as pigtails, regulators, and other items that may need replacing and when they do, the vacation stops until they are fixed, especially in winter.
2: Basic key copying. Sounds crazy, but sometimes keys are needing to be copied, and you will be the only shopkeeper that can for miles around. If you get a Hillman Axxess key duplicator that uses cartridges, that can do the most popular keys. One can also expand to automotive keys (ones that are cloned) as well, if there isn't anyone else nearby that makes those.
Those are the main additions I can think of, as most was covered. Keys and propane stuff are the main things that come to mind that tend to be hard to find.