I used to be a truck driver and snacking to stay awake can be a Bad but nessasary habit. But I have to say that you can move past it and into health. These are some suggestions but they may not work for you.

1) if you are already used to one meal a day why not try intemittent fasting.

2) Pork rids or nuts can help. When I was a trucker when I had to go thorugh what is know as the bewitching hour I always had gum to chew. the chewing did more than the calories

3)when you are in ketosis your body will not tire as quickly. so try some magic bullet coffee when you head out and try to have some fat when you are returning.

Best of Luck to you