I've been to Gettysburg several times.
Devil's Den is a favortie place of ours to take the kids so they can let out some energy climbing the boulders.
It would be more difficult -as a visitor - to do this on a hot day without any shade.
So take them to a kiddy park next time. The Devil's Den area should relect the way it looked at the time. It was not created as a kid's playground. Perhaps you want them to add swing sets and monkey bars, but I don't.