With a little prep, this is no biggie. We moved from St. Louis to the North Austin area over a two day stretch and with lots of fish.
In advance, get the plan! Good start on that. If you find the Kordon bags good, if not still okay. Fish have been shipped for days before the bags were developed. A good place to start is by reducing the load of waste the fish will put out. Don't feed them for several days before the trip and don't use dirty tank water while they are in the box/bags. Get as large bags as practical and securely seal the bags. One way to avoid trouble is to bag and seal one bag and then turn it over into a second bag which you seal. This does away with corners in the bag where fish tend to get their heads stuck. Have a local shop show you how to seal if it is new to you. If using regular bags, use just enough water so the fish can swim well, but mostly trap as much air as you can in the bag as you close it to seal. They need air more than water. The car movement mixes the O2 into the water. No pumps needed.
One cheap way to go is bags in a box but it is real easy to buy a styro cooler from big box. Bag em, Box em, seal the box and don't look. If you keep them where you are comfortable, they are good to go. Don't set them on the floor where heat comes through. The seat is better. If you stop for lunch when it's 95, make it short?