I agree with @JacinLarkwell you can skip the food but you might stop half way and offer water. They may be too stressed to drink but maybe not. It will give them comfort to know you are still there too.Noted
If its only about 5 hours travel time, do you think they'd still need a snack with one of the stops, or just a drink of water to stay hydrated? I want them as comfy as possible but also considering the amount they poop!