Micro-Trains makes a mixed pack of collapsed and raised trailer hitches for flat cars. I would think you could trim the excess off the collapsed one to utilize the hitch.
Or, just get some styrene strip and make your own. Cut to look like the hitch, drill a hole in it and voila, you've got a hitch plate to put on the A/P well car. Heck, thats about all it looks like Con-Cor did on my N scale A/P well cars...