If you buy this product, be sure to follow the warnings provided at the website: the maximum weight is 500 pounds and you should not use this gadget "when vehicle is in motion."
http://www.kotulas.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10051&storeId=10001&productId=11260&langId=-1&parent_category_rn=16551&top_category=10081 via Nerd Approved
http://bumperdumper.com/bumper2.htm
been around for years