A great hike is Salmon Creek, just above Ragged Point. Since you are at sea level, it all up and up and up, but it is worth it. Beware of tics, plenty of them. Boondocking is a bit harder. Along the ridge accessed by the Ferguson road are some dirt roads. Check out a good map for them. Great camping and views. 4wd is usually not necessary, but because of recent rains, that may change. The problem with Big Sur is access. The mountains are very steep right to the ocean which makes it hard to get into them, both hiking and roads .As a result, there are not a lot of trails, but the ones that exist are good ones. A good trail map or book would be worth getting. Tassajara is a good hour dirt road in, but they are not open to the public yet. They open in May. However if you want, you can volunteer there during the month of April and they will put you up and feed you. A cool way to spend a few days, not to mention the hot springs. Excellent hiking from there. If you can make it up to Half Moon Bay, absolutely go to Butano State Park. One of the last remaining old growth redwood stands in the State. Over the top, awesome, humbling, experience to be there. A very interesting place to stay of visit, although I know you both are campers, is Deetjens . Look them up. Go slow, there is a ton to see and places to stop. Personally I would get out of San Luis quickly. Not that is bad, not at all, I love the place, but the areas up North are so much better you will need the time. Too bad you only have 4 days, 8 would be better.