What is the danger of backing the tractor under a trailer when the trailer nose is set too high relative to the fifth wheel?

1. The tractor will stall its engine immediately
2. The trailer kingpin may slide over the top of the fifth wheel (high-locking), failing to couple and damaging cab components
3. The air brake lines will get sucked into the radiator fan
4. The fifth wheel plate will lock in a tilted-forward position