What kind of weight are you pulling?? I have that bumper, i boxed in a section on the inside of the bumper around the receiver area and out to the shackle mounts both sides.
I had a 10" drop hitch & was pulling 2000lb trailer, tongue weight maybe was a few hundred pounds, no problem. After the mods, the bumper seemed totally solid, flex through out the unit was dramatically reduced & i was confident towing with it.
Just an idea.