Longest fifth wheel at most Yellowstone Campgrounds?

I stayed at Fishing Bridge with a 34 ft fifth wheel. I BARELY fit. When I left I had to pull forward about 5 ft into the 'woods' in front of the campsite (on the other side of the road)to get back out of the site. I now have a 38 ft fiver so am pretty much out of luck in Yellowstone.
Staying in the park does save about an hour or 1 1/2 hour drive time tho. And to me is worth it if you fit.