I have seen many plans for using the Hitch Receiver for other things.
I have, in my basement, either an 11" or a 13" Drop/rise hitch adapter, This takes a standard ball (I think I have one that is a drop /rise receiver as well) both are common items (though special order) at RV dealers or Hitch World.
Of course you can get smaller ones (Say 8" or 4") Get one that is designed to take a Ball though, not a receivewr.
Now get a carraige bolt, of teh same size as teh hole in the thing, about 3" long, with nut.
Drill out a plywood slab to that same size, (Center drill
Add washer adn bolt, bolt to hitch. You now have a "Table"
That easy.