Take rubber for sure. The water is cold there in the winter.
The road from Mulege to San Isidro is pretty good, slow and rocky but you don't need 4WD. If you are coming up from Todos Santos just stick to the paved road north through Insurgentes (don't take the turn to Loreto) to La Purisima. From there it's only 35 miles on a graded road. You can take the north road out, it takes you right up to San Ignacio. It's over 100 miles of dirt road but it is in pretty good shape and it's a cool drive.
It's beautiful here, the campground is open, and there aren't many people here this time of year. Just so you know, it's not a winter surf spot so you never know if you are going to score. The last swell made it around but it is rare, it can be flat here for long stretches (even in the summer). The fishing has been fun and, weather permitting, I'm always up for going out. You can learn more about he campground at
www.scorpionbay.net.
Send a PM if you are headed up this way. My place is right at first point (gringo hill). Just ask anyone where Jack lives and they will point you in the right direction.