received the following from FCA on the flat towing issue with shakes and wobbles:
"Customer may experience vehicle shake while recreational towing/flat towing over rough roads. If customer is experiencing vehicle shake while recreational towing/flat towing, a Mopar Accessory kit (68321424AB) is available to improve flat tow towing behavior. Owners may contact their local dealer for purchase and installation. The Mopar accessory kit 68321424AB provides power to the Electric Power Steering (EPS) system to allow the vehicle to benefit from this system during recreational towing/flat towing. Otherwise, the EPS system is inactive during recreational towing/flat towing."
I requested this response after receiving a page to insert into my owners manual with no real explanation for the change or if you installed an unidentified wiring harness what it does. This answer does not address whether the wiring harness also allows for battery charging while towing that the manual says needs to be done.