I still haven't given up hope on building my own bumpers and here are some musings on a hybrid (Steel and Aluminum) setup for the back. I went with the typical offroad steel spindle pivots and set them wide. They tie in directly to the frame. The bumper will be all aluminum and basically bolt on to the steel. I took this one a little further than the last and am pretty happy with the result. I think I can do this one pretty easily. If the spindles prove to not be as strong as I had hoped, I can redo certain portions of the bumper. 273 lbs including the 100lb tire and the storage box.
One thing I like here is the ability to swing the arms almost 180°. This way I can use the box as a galley and face it toward where the awning will be and cook right off the bottom hinged door. Top door will hinge up. Box will still fit 4 Jerry Cans.
Still gotta work out the in bumper storage and a strong latching mechanism. Probably use spring loaded pop pins to keep the arms in position. the Brush guards also prevent the arms from swinging around and hitting the van.