Question about wrecks while towing a 5th wheel

IMO if the truck and trailer combination is straight, and the hit is from directly behind, I see no reason that the trailer would jack knife rather than ram straight ahead.

But why worry, if it happens, it happens. No amount of worry will keep something like that from happening. Do the best you can and let the what-ifs fall away beside you. Life is too short to worry excessively, and especially about thing over which you have no control.