The NE entrance to Ystone is a hellish ride for an RV. I've done all the entrances and prefer the East entrance out of Cody. You have to climb Sylvan pass (we had snow up there this past July 8) but puts you right into Fishing Bridge.
Tom and Katharine
'07 Winnebago Tour 40TD, 400hp Cummins
'17 Winnebago View 24V, '02 R-Vision B+
RVing for 20 years & 200,000+ miles