We took lots of road trips with the kids when they were smaller. My friend has 2 kids and my 2 grand kids I am raising.
Our trip itinerary was based on parks, McDonalds, Burger Kings, elementary schools, kid friendly places with play grounds.
We would get up in the morning and eat a huge meal at the hotel. We figured how much it would cost at McDonalds for breakfast and that was nearly $50 so if the hotel room was even close to $80 the cost of breakfast was about half of that. So the room really was cheap.
Then we got on the road.
We'd stop mid morning someplace that had a playground and have snacks and bathroom time. It could be McDonalds or some other fast food place with a wonderful playground and we would get everyone the fruit parfaits. The kids love them and they are not totally unhealthy...lol. They also have other yummy items that are quick to eat and not so bad. The kids need the play time, it not only exercises their body it also exercises their brains.
For lunch we'd stop someplace that had a sit down meal area. It seemed to make a really nice break from the stop and play ideal. We would not "linger" but we'd take our time and eat a good meal.
Then if the kids needed it we would go to the local outdoor playground. If it wasn't too hot or too cold. If the weather was nice and they could run amok it was wonderful for everyone to get out and stretch their legs. Bathroom time for sure. If your kids have a big BM after eating a large lunch you may want to take some extra time here to allow them that big poopy diaper.
Back on the road again. This time would sometimes take 2 of us to get my grandson back in his car seat. He knew what it meant, more time just sitting. It was sometimes a chore to get those buckles together.
I cannot say there was ever a time during this afternoon time that everyone, even the big kids, didn't fall asleep or sort of veg out. It's the combination of the food and the movement of the vehicle. I always tried to stay awake and visited with the driver to make sure they were not sleepy too.
When everyone started moving around, arguments starting and such we'd stop for an afternoon snack and bathroom time. This would be a quick snack with a bit of play time too.
Since your children are not into movies and stuff they are going to need this even more than other kids who will watch a movie then want to stop, watch a movie then stop, etc...
Back on the road.
For dinner I would say, depending on how close you are to your goal destination, that I would want to stop and just do something fun. Go to a mall, go shopping, take an hour or two and just do something else. It will refresh everyone and the mental break will be wonderful for each of you.
I know this seems to be taking a lot of wasted time but if she is not going to sleep she is going to be super cranky from sitting on a hard seat all day. Those car seats are hard, the foam in then compacts with their weight and their hineys get sore. Taking lots of breaks and doing other stuff will allow her mind to not dwell on the ride.
I would say after dinner that if she does not go to sleep I would surely do a hotel for the night. I would imagine she will be super cranky by nightfall and want to lay out and sleep solid. I think this may be something you'll have to consider. Especially if she does not sleep all day.
The other option is to eat dinner at home, a nice family meal, then get in the car and start the trip. Of course the driver needs to have had time to sleep during this day. Then the driver should drive all night. When it is morning the driver goes to the passenger seat or the back seat, if it's a van or vehicle with a 3rd row. Then the other parent drives the rest of the way. I like this idea if she would sleep at all. I would recline her seat a tiny bit so she would not be a bobbing head. I did this all the time when I had the kids and didn't want to drive during the day. I like nighttime travel best. The roads are less populated and it just seems to be a nicer drive.