I'm a full-timer and refrigerator/freezer is loaded and on all the time (mostly propane). One of the interesting things about people is that no matter where you go, they all eat food. So, it is available everywhere. Unless going to a VERY remote area (AK, maybe??) or have very unique tastes/requirements, you can stop at a store and get what you need, forgot, or need more of!
I shop pretty much exactly like I did when in a S&B's. The only difference is that I try to get rid of the "extra" packaging that nearly always exists. Especially cardboard boxes. This is largely for space but also due to the old 'it attracts cockroaches' claim (I have no idea if it is true).