Driving a motor vehicle requires 100% attention 100% of the time. You cannot be distracted from the road, from the vehicles around you, what they are doing and how this impacts your driving. You need to be alert to this ALL the time.
I must say, I 100% agree with Michael, mail that phone home, or at least, switch it off. (I had to do that when I found myself becoming too reliant on my gps. I switched it off.) Get good maps and 'know' where you are at all times.
Your stress is exacerbated by driving after dark. It is much more stressful than driving during daylight hours. Try to be on the road by the latest 9am and get off before the sun sets. That should give you 11 hours - ample to cover the distances. Don't forget, you have an extra three hours heading west. When you get to your destination, get to bed early. Don't be up till all hours, fiddling with the internet. It is sleep you need, not chat.
But most importantly, drive carefully, drive safely and stop frequently. Remember, it is better to arrive late, than dead on time.
Lifey