I have a 14 ft Boston whaler that I pull with my Axis 500 and am able to launch it in a small lake behind my house. My Axis had an adaptor but as someone mentioned before is useless. This adaptor, which I found at Harbor Freight, fits the socket but I had to drill a hole in the top (90 degrees) from the existing hole to lock it in: https://www.harborfreight.com/automotive/trailers-towing/hitches-receivers/ball-mount-hitch-with-2-inch-drop-94902.html
I also had to adjust my tongue weight on the boat trailer based on the Axis hitch specs limit. Hope this helps.