We travel a lot with our dogs.........We have a trailer now with a dog crate under the bed for security if we ever have to leave them for short period.
But we used to travel many miles with just our Jeep and three dogs in the back harnessed in. Water water and more water.....it is important to have plenty of clean water to drink for the dogs. We carry large gallon bottles for "just in case times"......The food they are used to, which can be a bit difficult when you feed RAW like we do, but we manage. I just freeze and carry
You are lucky in The USA, becasue you have Hotels/Motels that allow pets. We have very few of those. So I would find out where the ones on my trip were.
Good leashes/collars of the non slip variety. We also have info (mobile phone number) tags on our dog collars. Our dogs also have RSPCA tailwaggers Club Tags, which means there is always a place that will take them in case something happens. We have RSPCA's all over Australia and when you belong to the club they have all the info as to what to do with the dogs in case something happens, say an accident or lost dog found.
We camp mostly and just chill out. Our dogs love to travel and just sleep. We have lots of pit stops, usually 2nd hourly. We keep to our routines of feeding, even if it means an extra stop. We go on lots of 5-7 hour one way trips and the dogs have never been an issue.........So much easier compared to taking our horses
Enjoy your trip, I am sure lots of people will have many more ideas
Ronnie
PS we have a non tip bowl in the back for the dogs to drink out of. The water level stays low, but it has a lot of water in it