Truck stops are usually fenced in with fuel, a place to sleep if you don't want to sleep in your cab, somewhere to eat and some kind of communal area if not a full on actual bar.<br/><br/>If they were at a place that was fairly well traveled and was reasonably well heeled they could well have a good month or two worth of supplies. Though they would almost certainly have to keep their heads down if they didn't want the dead outside the gates to know they were in there.