The porposing effect you feel is common. When there is a drop between slabs of concrete it will happen every time. It's because you have this thing hanging off the back bumper. You can soften it by slowing down and putting good shocks on the truck. Check your tires. The may be too weak for the load. That will also add to sway. Don't be afraid to max out the air pressure. Check the sidewall of the tire for pressure. I added StableLoads to my truck and they helped a ton. Some roads I had to slow to 45 on I can now run at 55-60.