I did a lot of stupid things on horses when I was a kid. I certainly don’t want my kids doing what I did! Fun, yes, but I was a complete idiot. I would kill the kids myself if I ever caught them jumping over sharp objects, for just the reason you mention. Trash themselves if they must, but the nearest horse ER is an hour away (Marion duPont Scott) and there are extreme limits on what can be done to fix a busted horse, as witness Barbaro.
It’s sobering when you see a guy who used to be huntsman at a prominent hunt and a steeplechase rider driving his motorized wheelchair up and down the road. (You may know who I mean since you hunt and the hunting world is small.) He didn’t hit his head, but broke his neck. Unfortunately even a $400 GPA won’t prevent that, and I wish I could think of a way to prevent such neck injuries (a helmet with springs attached to your shoulders??).
But it does give one pause. I don't know the huntsman you mentioned, is he in GA? I only hunted once out of GA, in NJ many, many years ago.
I don't think there's any protection for your neck, other than to ride in the back seat and don't take chances on a doubtful horse. My own mare I would ride anywhere, she is dead set reliable. She did fall DOWN with me once, slipping on an unexpected patch of mud on a hillside, but she tucked her front feet and waited calmly for me to get up first.
But necks break on diving boards and on swing ropes, too.