Let them take their emergency kit that includes much of what is listed above.
Beyond that only take what you would on a typical day hike, pretend to get lost and survive the night.
It's actually a lot of fun for the boys to team up, build a shelter and work together to tend their fire all night.
Not a lot of sleep happens but it had been one of the most talked about and favorite campout for my sons and our scouts. The scouts look forward ttyl it each year.