I have seen 5th wheel adapters that allow you to tow a boat on a trailer with a regular ball hitch. They have a plate with the 5th wheel pin in the bottom and then an arm that extends off the back and down to a receiver which can take a towing ball. Their relatively heavy and the ones I've seen have forklift slots on the plate to lift them into place. Any ideas where to buy one?

We have a 5th wheel conversion from Popup that converts from 5th wheel to gooseneck ball at http://mrtruck.net/popuprv.htm