It is a work in progress but I call it the "Balcony Bumper".
It has an all Aluminum Diamond Plate platform that slides out from under the rear bumper and provides and additional 10 sq ft of floor space. We use it for off the ground showering, Porta Potty space...
Sometimes I set up the Porta Potty/Shower Tent right off the back of the Balcony; with the van's back doors both open it provides the privacy to roll out of bed, out the back, on to the Balcony and in to the Tent to do your thing.
Eventually I want to create a enclosure that hangs off the Penthouse top, attaches to the doors and encloses the complete Balcony area, eliminating the need for the tent.
It has supported well over 500 lbs and could also be used as a carrier for fire wood or ...
The guts of it are all steel and tied to the Class IV Hitch; with side extensions that have receivers for the steel spindle and tapered bearing swing outs. I've finished the tire carrier on the left and will be adding an additional carrier on the right for generator and storage box.
Since this picture, it has all been Powder Coated black and a aluminum Bumper Cover has been added. The bumper cover is not finished as it still needs to be contoured, filled and polished or Powder Coated.
Here are a few more pictures.
You can see my 30 gal water tank is also protected by it.