Rear bumper mounted receivers are notoriously BAD! First that's not really a bumper. It's a dump hose holder
Seriously, the metal used on the bumper is extremely thin. Second, it will literally tear apart at the welds when the cantilevered weight of a bike rack and bikes is added. I've seen it happen. The best option for a bike rack I've seen is where a class IV receiver is welded to the frame of the trailer. Cost is about $400. Then a good receiver mounted bike rack is secured to the receiver and the bikes ride safely and securely. Some 5er's are equipped with a "cargo" rack that can be used for bikes with a bit of modification.