I would take I 80 to Rawlins then the 287 to the 26 you will go thru the Towogetee Pass which you will find to be beautiful and a good pull up the grade but I had no problems with my 36 foot Hurricane pulling my jeep .
We stayed in the Tetons at Coulter Bay as our base camp and drove our jeep into Yellowstone south entrance daily. Good luck and happy travels
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