Definitely have them bring their own drinks and snacks. I would add a jar of drink mix like lemonade, etc. in case they run out mid-trip (it's amazing how much teenage boys can go through in a day). Be sure they know it's up to them to make their snacks and drinks last through the trip - there's no running out to the store if they run out on the second day.
I would have each boy plan one hot meal and be the head chef for that meal. That will give them some input into the meals and reduce your workload. And, after the first trip, it may build a bit of fun competition between the boys as to whose meal is the best.
Are you limiting electronics? If not, will you have hookups to re-charge devices on demand? If you don't have hookups at the campground, then you need to be clear on generator usage and/or house battery limitations. 4 teenagers' worth of electronics could run through a battery pretty quickly.
Other than that, I think it will be fine. You know them, they're good kids, and they've got a wilderness to enjoy. Just a reminder here and there about camping etiquette (check voices late at night and early mornings, etc.) and they'll be fine.