Anybody know how far away the closest cell reception would be? We have people in our group driving up later and need to tell them exactly where we are

There is a spot of about half a mile of reception approximately 3-4 miles south (toward La Canada) from the campground.

They should research where there going. And there is no cell reception up there.

Your best bet is to download offline maps with directions to the camp. I didn't find any spots with reception when I got up there.