I did it in my 3 yr old 85 just this past July. Actually I was able to top off (almost) on a 30A outlet at Old faithful, it seems to have been removed from PlugShare so they may have turned it off.
I left the Old Faithful area with about 240 mi range IIRC, just before it finished but had already tapered to a trickle. (My S85 topped out at 245 miles just before I started my road trip a week earlier.)
Going into the mountains about 80 (?) miles before Sheridan, I was really scared. I got to the general store on the plateau with 52 RM left, and 46 miles to go. I arrived at the Sheridan SC with 42 miles left! From the top, only 10 RM used. I gained 15 miles on the way down. If I had driven by the Old Faithful entrance with 200 RM remaining, I still would have made it; but I wouldn't have thought so as I approached the mountain.
So if you can make it to the top of the mountain with 20 RM remaining or so, you should be able to just make it to Sheridan. I would not use heat during this trip if you do try it. Also I stuck to the speed limit and sometimes slower.