Although my hitch mount rack came with an insert from factory, it is a single bolt (just like the ball) to remove from the insert.
I suggest looking around, you may find one with a single bolt that you can simply remove from the factory insert and bolt onto your receiver.
Like this.... (mine is more like the second one.)
http://www.discount-trailers.com/hit...-bike-rack.htm
or this
http://www.buzzillions.com/reviews/x...-mount-reviews