This drink mix has been working for me.
To make about 8 large bottle mixes:
1 cup sugar
1 1/2 teaspoons salt ( about half regular salt, half lite salt for potassium)
2 packs natural lemon koolaid

2 heaping tablespoons in a snack size ziplock bag for one large water bottle. Approximately 100 to 120 calories. I bring a few bags to mix at water stops.

This has the same amounts of carbs and salt as gatorade.