Camping?

I'm kind of in the same boat. A few times last summer I just showed up in the evening and got lucky. The Ventura area is a good bet because there are a few state and county campground to try. Emma Woods is one we have had good luck with. A few weeks ago we really wanted to go somewhere so we went to a private campground in San Dimas. We got a spot with an awesome view and the kids liked it. It was only 20 minutes from home, but it got us out. Every year I tell myself that I'm going to book 7 mos in advance and every year I don't. Maybe this will be the year.

Right now all of the coastal areas are packed its a roll of the dice if you can find an opening.

http://www.reserveamerica.com/

How about Alamo mountain? Dry camping at the top 7,000 ft. Make sure south gate off Hungary valley road is open. I used to call the ranger station.

Can you shoot for weekday trips? Most people plan their trips for Thursday or Friday through Sunday or Monday. If you can do it, shoot for Monday through Thursday and you might be able to find some spots.

You might pick up a book on California camping that lists campgrounds - they often tell you if it's reservations or walk-in only. If so, then if you hit the walk-in only by Wednesday early, you should be able to grab a site before the weekenders get there.

The other suggestion is to check recreation.gov for availability 5-2 days before your arrival date. There might be a last minute cancellation that you can nab (but you have to have at least 2 days before your arrival to reserve online). You might also try calling the campground owners (state park office, national forest station, etc.) and asking if they have anything available last minute that you can reserve - the worst they'll do is tell you no.