We were there a couple of months ago. I wouldn't try to fit a 40' in any of the interior sites, but that's just me. I don't remember site 59, I just remember how claustrophobic that area was.
I would stick to the outside of the loop. We stayed in site 4 with a 35'; you should be able to fit there. 3 and 2, if I remember correctly, were also long enough.
You might check out the other loop - 90-100 or so should be long enough.
Best of luck and enjoy your trip!
2015 Jeep Willys Wrangler
2014 Fleetwood Bounder 33C
States camped: all but Hawaii
more than 1700 days on the road