Still need to know the approximate location of your destination in Arizona. A lot of difference between Tucson, Phoenix, Flagstaff or the Grand Canyon -- Tucson and the Grand Canyon are about 300 miles apart. There are many different routes to go.
What I would do is open an atlas and start looking at your starting and ending point. What routes appear to go the way you'd like to go? There's no one "best route". Plan your stops around 350-450 miles apart unless you are stopping along the way to see something. When you're towing, you probably won't be traveling at 75 mph, probably more like 60 or 65 mph, depending on the state regulations. In any case, you'll AVERAGE about 50-55 mph, which means a 450 mile day will take you around 9 hours. Your stops for gasoline, restrooms, etc., will take as long as it takes your slowest person.
Food ... well, some areas are still shut down with only drive-throughs and takeout available. In those areas, you will not want to tow your rig through a drive-thru, and many drive-throughs don't want walk-ups. With a travel trailer behind you, I'd bring as much of my own food as possible. Depending on what you like, Arkansas and eastern Oklahoma have some great catfish places. If you end up on I-40 going through Amarillo, the Big Texan is a great place for steak, and there's an RV park nearby. Drop the trailer and drive to the restaurant, though. The night we were there, the place was packed and there wouldn't have been a place to park a long rig.
We could be more help if we knew where you were headed in AZ.
Donna