Since you are making this trip in winter, I want to give you some tips about weather. Maybe this is something you are already familiar with.
Since we are not sure of your route, that can make a difference. You do want to watch weather reports and predictions and avoid blizzards and snow storms. Crossing the middle of the country, the plains states, there can be lots of wind that can cause problems if you are towing something. Please make sure you have plenty of gear for bad weather, as well as food and drinks, in case you get stalled, stuck or something for a while.
Out west, towns can be far apart, so you want to watch your gas gauge and make sure you have gas to get to the next place. I'd also make sure I had good full sized spare tires. You could have a flat or other tire issue and literally have 100s of miles until you could get your tire repaired or replaced. Wyoming is the least densely populated state, and therefore, the place where the services are far apart. It is usually very windy in Wyoming.
My aunts and uncles always discouraged me from traveling through Native American reservations, especially Pine Ridge in South Dakota. I have driven through several over the years, but there are not many resources to help you if you have trouble with your vehicle.
Have you ever been out west?
Many places are popular in the summer and there are many restaurants and places to spend the night in the summer, that will be closed in the winter months. If you can, you might want to check out what is available in places you want to see, such as Yellowstone.
Yellowstone is great, but large. The Old Faithful geyser is one of the more popular attractions there, but you have the opportunity to see bison, elk, bear. I've seen coyotes there.
The Black Hills of South Dakota is a very popular tourist destination. The roads through the Hills wind around. More popular touristy things to do there are Mt. Rushmore and Crazy Horse monument, but there are caves, lots of museums and exhibits, wildlife, archeological sites. The Badlands, east of the Hills, is also a popular tourist destination. Wall Drug is well known and large, blocks large. It is in Wall, SD, east of the Hills. Many people like to stop there.
Montana is a beautiful state, but can be so cold. It is a long way across Montana. Also, towns are not close together. It used to have the highest speed limit of all states, and it may still. Maybe 90 mph?
I may add more later. I hope you have a safe trip!