Yes I think sleep is the first priority to fix. Getting liver and brain glycogen storage up is probably the best thing, but can be tough. Focusing on frequent feedings, every 2hrs if needed, quality protein, carbs and coconut oil. This is why sugared milk could be highly recommended, covers all the bases and would be portable, sounds like you are on the run around the clock. Feeding/drinking/sipping every 2hrs should keep the stress hormones down, low blood sugar is a big stressor. Juice or even cola would be helpful.
I did stock up on lactose free milk, and a bag of dextrose. I've been adding a teaspoon to a glass. This winter is looking like it's going to be a tough one, so I'm going with your recommendation and keeping the milk in the truck with me.