IMHO I'm not too sure that the safety strut bumper brackets are as good as they look. I think they are snake oil. They only cradle the bumper and do nothing to stop the rotational force being placed on the bumper by the added weight. If you are still welding platforms to the bumper you are still welding to very thin metal. Too much weight trying to move up and down is the trailer bounces on its axle springs.
Even if it helps some and the bumper metal doesn't tear where it is welded to the frame it will more than likely tear where the platform is attached to it. Especially if welded to the bumper using receiver tubes. The best option is still welding directly to the frame.