We took an 8 week cross country trip in 2016. We traveled 10,000 miles. Most important thing to do is to remember tow vehicle maintenance. Oil changes were #1 for me. I carried a gallon of oil, gallon of antifreeze, Gallon of windshield washer fluid along with rags, gloves. All in a plastic container which I carried in the back of the truck. Oil changes I went to the local Ford dealer while we were at a campground for a couple of days. Also carried a tool box in case of something breaking or needed minor repair. I took a lot of things out of the trailer that I knew that I would not use. Don't think there was anything that I wish I had that I did not bring. There is always a Walmart somewhere in the area..
Have a good time and just look at what you have in the trailer and think I'm not going to use this (snow shovel)..
Bill