I have a 2010 and have the curt receiver that pulled a 31' toy hauler. I'm pretty sure I was overloaded though as you can see the angle the receiver was moved to.
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I have a Mopar accessory receiver add on and use a weight distribution hitch. I tow up to 6,000 lbs. Have had the hitch push up but not quite as much as that. It was due to the slack between the bolt and the bumper support. I went to the local hardware store and found a bronze bushing that fit the main bolt on the receiver that goes through the bumper support. There was some slack left but not much. That cured my hitch lifting problem.
The Curt hitch has a conical bolt head which is meant to center the bolt in the bumper support. It requires 200 ft lbs of torque. That may be the problem if the bolt is just not tight enough. Use of the bushing like I did would probably raise the bolt head where the plastic plug would no longer work. There is a cap available for hex bolt head from e-trailer but would not work on the conical bolt head.