The best time to eat lunch when backpacking is from about one hour after breakfast until about one hour before dinner, continuously. In other words, frequent small snacks of complex carbohydrates all day long. That way the body has a constant source of energy available and the Scout is less likely to get too tired. We generally recommend nibbling on trail mix all morning and afternoon, with a little more substantial food for lunch. Carbohydrates come in two main types, simple and complex.
Simple carbohydrates are sugars.
Examples are breads, cereals, beans, pasta, etc. Trail mix is a good snack food for the day-long lunch. You can also mix your own and put in exactly what your Scout likes. Most trail mixes consist of dried fruit, nuts, seeds, etc. You can also throw in a little shredded coconut and some dried banana chips, if he'll eat them.