Pulling 5th wheel through Yellowstone

Going through the park with your rig should not be an issue. Getting there is a different story. If I understand your question correctly you would like to take 14/16 west from I90 to Cody then on through the park. If that is part of your question, I would not take 14/16 west from I90 with that size rig. Getting to the top of the Bighorn Mountains from I90 on 14/16 is treacherous at best with your rig. It’s a great scenic road and fun with a car through all the S turns and switch backs but not pulling a 40 ft rig. I would plan another way to get there. Coming into the park from the north through Mammoth Hot Springs is a safer way in and also very scenic along the Yellowstone river.

While in Wall, SD make sure to stop at Wall Drug, they have the best cake doughnuts in the whole world and coffee is only 5 cents!!!!!