what most people don't realize about making their own.......
they want to put the load on the aluminum battering ram rear bumper--thinking it can take it,
if you look up under it its held to its brackets by two 3/4 aluminum lips on top and bottom of the rubber cushion that's inserted in the pocket, and those lips often fail with NO weight being pressed down, Just from random bumping into a parking lot wall etc. you try carring a trailer or whatever with the load on the American rear, you are asking for trouble--and it could be fatal to some motorist behind you.

http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/280370-large-300d-300cd-parts-post-10.html