If Rafter J Bar interests you,
H E R E is the map of the campground, and
H E R E is descriptive info on each of the sections. There are actually 6 rather than 5 sections, so there's definitely something for everyone.
I usually stay in either the Ranch Camp or Lower Ranch Camp. The Ranch Camp is in the trees, and could be a bit tight for a 40ft 5th wheel, but it's doable in some of the sites, and there are some pull throughs. That said, I watched a guy with a dually and a big honkin' 5th wheel BACK in to a very tight spot, in between trees. His skill level was quite high!! :C
The Island Camp seems to be a preferred section for folks with bigger rigs and no need for the shared showers/restrooms. It's a very impressive section indeed, lots of space between sites.