Dutchman and others had lots of good advice and it will usually be sufficient, but the campgrounds can still throw you an unexpected curve.
Last summer I ran into one in an Oregon State Park where I would fit in the site. It was at a right angle to roadway. I knew this and knew I could get in, BUT when we arrived we found there were three trash cans protected by concrete posts in the road directly opposite the site! No way to get in there with my rig!
That was the only one out of 12 Oregon State Parks that I could not get into. A couple of places took some jockeying and in a couple I had to park the truck away from our site.