I'm not sure you can't get one with a heavier rating (Dual hitch adapter) there is also another solution that might work (it basically bolts to your cross bar)
I have seen, in the past, a bicycle carrier that was designed to slip over and attach to the 2" Square "Tong" of the Blue Ox (or other) tow bar.. This may be your best solution if you can find 9it.
NOTE: Blue Ox makes a device that goes by assorted names. "Hitch Immobilizer" or "Anti Rattle Clip" if you add a bicycle carrier USE ONE That towed will toss the bicycle around a bunch without it.