I stayed at site C-77 in Fishing Bridge with my 40 footer in 2008.
You should call the Fishing Bridge Visitor Center (307-242-2450) and they will give you the direct line for the campground. The nice lady there will tell you what sites can fit your rig. The general 1-800 campground reservation number is not too helpful.
Tom and Katharine
'07 Winnebago Tour 40TD, 400hp Cummins
'17 Winnebago View 24V, '02 R-Vision B+
RVing for 20 years & 200,000+ miles