That thread considers towbar mounting - which is a bit more engineering than is really necessary to carry a bike. I'm thinking more about the sort of rack you would put on the back/boot of a saloon car, or perhaps one to fit in place of a luggage rack, but with similar fittings. Perhaps a custom rack would be needed - if you had quick release brackets, they could be used for both types of rack interchangeably. For one road bike it need only carry 10-12kg, and as the rear lights and plate are mounted low, it wouldn't need to be high.
