Yeah I thought about that. That's why I'm not in a hurry to buy a mass fabricated rack. I'm going to find someone who can custom make it with plate steel on the lower section and heavy bars.
My biggest worry about the fiver coming forward is if I rear end someone. Fortunately the adaptive cruise control will prevent a rear end collision. On our current 6000 mi trip, the adaptive cruise has worked flawlessly.
If someone rear ends us, unless it's a semi-truck, they're going to be a lot less weight. And that crumbling splintering rear end of the trailer will take a lot of the force.
I do wonder how much force it would take to tear the fifth wheel hitch off.
In either case I still feel safer in our combo than having my kids ride inside a wood and fiberglass box.