That is one option and not unlike what I use (I have a custom made dual adapter with 4 drop.. the straight part is a ball mount where the bicycle carrier mounts)
Another option is a bicycle carrier that slips on over the 2 inch square bar and clamps down.. That works well .. very well in fact.
Whatever you use Blue-ox sells a device called a Hitch Immobilizer Use at least one (On the motor home to adapter junction) this greatly reduces motion of the bicycle (s) on the carrier. GREATLY.
http://www.amazon.com/Blue-Ox-BX88224-Immobilizer-Receiver/dp/B00403LNQI This is an upgrade from what I have
