Many prefer not to screen entrances for long moves. If very hot stop every other hour and hose the colonies with water. There should be no shifting, not to mention dropping of the load. A hive cover that flies off a colony could go through another vehicle's windshield and cause a terrible accident. All lids should be nailed down or secured in such a way there is no possibility anything can fly off.
Some states require all bee loads to be screened or netted.
Colonies should not be left sitting on a stopped truck during the day. The field bees will fly around and the bees can overheat quite readily. Many people prefer to load their bees at twilight and unload them at daybreak. Stopping for any reason can cause problems. Be sure the vehicle is road-worthy.