It would only take cutting the beam, welding on a hinge and a clamp to secure the boom together while riding. A better option might be a sleeve that would slide in place over both parts of the boom and bolted in place.
I was thinking about this because I'm considering a new car. It either has to hold my Rover in the back or have a receiver hitch for my Alpaca Carrier. Most vehicles that offer this get terrible gas mileage. A foldable Rover would fit in a smaller SUV. No, a Traveler is not an option because of it's weight limit.