I must share this near disaster story.
I had a two inch receiver welded onto the 2X3 rear bumper, as well as raising the spare tire holder to fit the addition. I added a bike rack, two bikes and off I went for a couple of weeks.
Got home and thought the receiver looked to slant down. Closer inspection revealed the problem. The metal had torn on top of the bumper at the old weld of the frame and bumper junction. A gap of 1/4" had opened presumably due to the bounce of the bikes and rack. My welder said the metal was weak and the original weld was poorly done.
Imagine if that bumper had fallen off on the highway! A spare tire and mount, two bicycles, and a steel bumper would have caused a crash potentially killing someone.
The fix was a triangle of metal welded across the joint.[ I also had added a pair of scissor jacks ($10 each from a wrecker) to the end of the bumper as stabilizers. They tuck up nicely behind the 3" bumper.]
So a warning is made to all bumper packers... reinforce!
BTW, I could not find any other suitable way to carry the bikes. Hate not seeing them back there, but they could not fit up front between the tow vehicle and the trailer.