From what I have read, the metal the bumper is made of is so thin, it will actually rip under the stress. The weld is still in place and the bumper peels off like a beer can.
I put the 4 square reinforcing brackets on mine, and then used the bike rack that has 4 separate mounts ( 2 at each side of the back of the trailer ).
S jumped up and down on each one as hard as I could, and I'm 225, no problems.
That said, when I put 75 lbs of bikes on it, I also strap everything so tight it can't even wiggle, and then strap to the spare tire for added safety.
It's still a gamble, but a lot safer than some of the stuff I see on the road.
https://www.amazon.com/4SQUARE-SafetyStruts-Prevent-Bumper-Failure/dp/B00JASCNEE
http://www.etrailer.com/dept-pg-RV_and_Motorhome_Bike_Racks-sf-Platform_Rack.aspx
2014 F 150 ecoboost
2008 Chrysler Aspen
09 Amerilite 21 (modified)
2013 Bendron 14' enclosed cargo
2011 4x8 open cargo