Hi and welcome to the forum.
I grew up around Mt Morris, went to Beecher Schools.
I worked for a locksmith for awhile and there aren’t any commercial locks for 2 3/4 balls that I know of. I don’t think it matters tho as thieves will wrap chains around the A frame and a tall hitch and take the trailer that way.
You can run a cable and or a chain through your rims and have a hitch lock: you want them to give up after a few minutes and move on our find easier pickings.
One guy left his ball mount/hitch locked in the ball turn backwards wrapped in chains around the A frame.
Good luck..