It's a great ride! Back in '12 we spent the night at Cedar Pass campground, near the visitor center in the east end of the park. It was late Oct and they were in winter mode. IIRC, only a small section was open, FCFS, and no hookups. It may have been free, can't recall.
Enjoyed the evening there, then drove through the park (40 ft towing) in the morning with several stops. Checked out Wall Drug, bought a souvenir fly swatter, and had lunch there before moving on.
Definitely do it!
John & Diane, fulltiming since '12 02 DS40, FL, Cat, '04 Element NHSO RVM103
John and Diane (RIP Lincoln, 21 FEB 22) RVM103 NHSO
Fulltimers since June, 2012
2002 Dutch Star 40, Freightliner, Cat 3126, 2004 Element