Last week I was kind of in your place. But you're lucky, we had practice at 7am until 1pm.
Anyways, what I did during that week, was get up at 5:50, and eat breakfast right away. You want to eat a good healthy breakfast. Try eating at least 45 mins before practice starts. Eat lots of carbohydrates, protein is good too. Eat lots of fruit, specially bannanas, potasium helps you.
Stay away from dairy products, like yogurt, milk, ice cream, and even though it's not dairy, peanut butter too.....that is unless you want to see them on the field. It mainly depends on you, like I have never puked at any practices, weather its track, football, bball, or ahy other sport. But the bigger guys puke more easily.
During practice, the best thing you can drink is Gatorade or something like it. The commercial is right, when you sweat, ou lose more than just water, and only sports drinks can keep you going at 100% for longer. Drink two cups of gatorade every break. But if you can't get any gatorade for whatever reason, drink water, I'd take 10 swallows of water every water break. Also, be sure to water up before and after practice.
Finally, during the 2-a-days, we had a 90 min break, be sure to eat lots of carbs during this time, some protein too, a little bit of fat doesn't hurt. Basically lots of fruit, and something like a sandwich I guess. Stay away from peanut butter and dairy products.
But most importantly, WATER UP, its very easy to get dehydrated with this hot weather. Oh, and don't think I'm BSing you, most of this stuff was told to us by our coaches. Hope it helps.