RV bumpers are not designed as bumpers. They are more like sturdy black sewer hose storage tubes.
They are made of thin metal and the welds to the frame rails have been known to fail when weight is carried by the bumper.
They sell reinforcements that bolt to the frame and cup around the bumpers. Highly recommended if adding a bolt on receiver to the bumper for bikes or small platform racks.
My Wolf Pup came with a factory rack. It looks like it rests on the bumper when extended. It does not. It has two pins on each side that hold it and the other hinge part clamps around the frame rails.