OK., I have a 14 sport with the 8 speed, hemi, When I bought the truck new, it did not have the auto park, than I read about that actor, name?? getting killed because he did not have the knob in P.
It have happened to me a couple times, so Read the BOOK, I turned mine on with the program stuff on the radio. Also turned it off later to see if it would turn off and it did.
Maybe you are talking newer trucks, I did not notice, It will not go int park if the speed is faster than walk speed, forget 5km ? so no danger to transmission, thou it does slam in hard when I tried it , my post office boxed are on a hill, so that is where it get tested a couple times.
So get your manual out and read it, I forget what section it was in, as it has been a few years. I could pull the book out and check, but all the books should be the same.
BTW, I have never messed with the seat belt , so don't know about that part.