This calls for creativity. Do you have a steel bumper? Or bungee to the existing bumper, or attach to a piece of wood and bungee to bumper, or use the screws in the existing taillights to attach.
Or take the bulb sockets out and put them in the existing tail lights.
When towing my car, I had a T bracket made up that fit into the car's receiver.
Harbor freight sells suction cups that pump up by hand, but I doubt I'd trust them.
Where there's a will there's a way.
(I'm assuming this is a short distance, not cross country)