300 is the loop you want for pet preferred. Its a short walk over to the dog park either by the loop road, or by following the waterway behind the 300 loop (it wraps around to the pond by the dog park.)
For a 40' 5th wheel, you will fit into most but not all of the sites, I was originally assigned I think site 312 and there was no way I could even swing the trailer in much less fit into that site as there was a tree in the back left corner "inside" the site box. I ended up in site 322 which I could fit my 3 slide 40' sanibel. Had I backed up a little further I could have kept my truck in the site as well, but since I did not I back in far enough I decided to park it in the overflow area. I had a golf cart with me, so I did not need the truck nearby and it left me with my steps comming out on the paved portion of the site.
The previous year I had site 335, it might be easier to get into and it fit my old 38' RV with gobs of room to spare. This year we setup our grand gathering and actualy requested the sites from 2 years ago due to the size of the my new trailer and it worked well for out grand gathering that year.