I commend you on changing to a two point attachment arrangement. Minimizing movement of the weight hanging off the back of the frame is critical to avoiding metal fatigue. Despite some comments about the designed weight limits for the OEM receivers,
any design that allows multiple G-forces to cycle on and off at a single point is bound to fail, probably with little warning.
We used the Mount n lock safety struts. Part number 1SNUHD. Just and adde piece of insurance to support the bumper. Between watching it in the observation camera and friends in our group following very little movement with the two arm tray