Bivvy sack, space blanket, cell phone, compass, map, water, fire starter, whistle, high energy food source. Some of the suggested items to pack up and carry along. It would take little room in a light pack or over sized fanny pack.
Leave a plan of where you are going. Write it down and put on dash. Stick to your plan. If you walk out and drive to a new watershed, does anyone know? You should drive into cell phone range and call. Who will know you changed your plan?
Perhaps you are of the ‘I don’t have anyone to tell. It is no one’s damn business anyway. I can take care of myself’ variety. Well, that is fine. Just in case read the mountaineering site so you can better survive.