You just need a bar that mounts onto the 3 pt and put a couple of disc hillers onto the bar. About the best way to do this is to buy one of those multi-tine cultivators where the tine plows mount on a bar and then buy a couple of disc hillers from a place like AgriSupply.
Attached is a picture of mine. A friend of mine gave me an old soil ripper that has its tine plows mounted onto a diamond bar. It was a challenge to mount the shanks of the disc hillers to the diamond bar, but my friend did this for me in the machine shop where he works.
You can buy clamps for the shanks to fit the square bars used nowadays.
The disc hillers, I think, will give you more uniform row spacing than using the potato plows because you'll run one set of wheels in the ruts made by the previous row. A big rock or rots might cause your tractor to do a dipsido, but the rows will still remain evenly spaced, all with dipsidos like the first one made.
Ralph