Another suggestion that I saw on a YouTube video also involves tape. Put a piece of tape at the desired height on the breaker bar that came with the hitch. Since you will have it out anyway in order to snap on the over center latches, it is convenient. And you don't have to worry about the outer jack cover possibly peeling off the tape.
As for the hole, that is my guess as well. Because of how my propane tanks are setup on my trailer, I was not able to use the supplied jacks. So I'm using an alternative method to jack up the bars.