"The problem is that the other dogs can see him under the camper and start barking before I even know they are coming. When this happens it is instant red zone, and his focus is so strong that nothing, I mean absolutely nothing can get his attention"
What is more important? This dog being a danger in a public campground, or you being with your best bud?
If you are considering using a device, equivalant to a Tazer to control this behavior, slow down. This is a problem for a professional. Someone could get hurt very badly from this dog. "Red Zone" behaviors can advance from yippy dogs to other creatures. This is also giving Rotties and large dogs a negative image.
BTW: If this dog attacked a small dog, I would not blame the owner for defending it.