Ken,

I'm just going to chime in here. I have a heavy 5th wheel also and experienced the jerking motion you describe. Kind of like the seat back kicks you pretty forcefully every now and then. Some people can get physically sick from that feeling. There are hitch suspension systems available that soak up this forward/backward motion and insulate the truck and passengers from the jerking/chucking/kicking type feeling. They are pretty sophisticated systems and work well but they are also pricey.

I was planning on getting one before I installed my airbags. After the airbags, I no longer felt the hitch upgrade was necessary. I think the jerking is caused by the heavy load on the rear end causing the truck to constantly engage the overload springs. Any motion from the trailer was quickly transmitted through the hitch and into the truck. The airbags however lift the rear end back up off the overload springs and place much of the load on the soft airbags which absorb most of the jerking motion. I was expecting to re-level the truck with the airbags and be able to carry more weight but I was pleasantly surprised by the added benefit of the much smoother ride.

If you haven't put airbags on your truck, you might consider them. The benefit of leveling and increased capacity are worth the price themselves. If it also fixes your jerking, even better.