I wondered about this because from the pictures I've seen of the PP it looks as if the head is fairly rigid in regards to up and down movement because of the way it's attached to the yoke.
We keep our camper on a seasonal site when we're not traveling. When I back in there's a dip at the edge of the road that causes both the nose of the camper and the back of the truck to dip down. The site also slopes gently upward towards the back and when unhooking the back of the camper is 8-10" (or maybe more, I haven't measured) above the receiver of the truck.
If I'm understanding all of this, the way to make the stinger level with the unloaded height of the receiver so it slides out smoothly is to use the tongue jack and WD jacks?