Just replace the fructose with more glucose and leave the other nasties out !! I suspect it's mostly marketing, if you make him something sweet and cold, he won't notice the difference to a 'sports' drink.
The main reason Gatorade helped the sports team who first used it so much, was that before then, the kids got no drink during a game at all, and several died from heat exhaustion every year. The rest is just marketing.
