FWIW I have an all-steel Reunel tow-bumper with similar swing arms (also tire mount and baja-style box). I haven't had a pivot issue, other than I did not like hitch noise that was transmitted into the door, so I un-bolted the top pivot from the door, and it is all bumper-only mounted now. Even though it is steel, I still had the latch holes all wallow out, so the arms have some slop in them now. I will have re-weld those, and hopefully find a better larch setup (I'm thinking maybe even automotive trunk latches so I can pop them open from inside too).
One downside of steel of course is rust. I just plan on periodically painting mine. Although, I would eventually like it powder-coated to match the front Buck-stop. Also, last week I spent a full day R&R-ing the bumper, so could straighten the bumper's mounting brackets, which I bent in the fall (the van
might have gone airborne when I hit a water-bar across the forest road at ~50mph, and there
might have also been a loaded car trailer hitched to the back of my hitch rack, which was carrying an array of coolers and dry boxes, which was hooked in a hitch extension so said array would clear the tire and box
).
If I did it all over, I'm not sure I'd go with steel again. Plus, these vans can use all the weight saving they can get, especially towards the rear.