Ubuntu – How to remove third Unity Launcher on a 3+ Screen setup

In this question, we learn how to select ONE display to show the Unity launcher on in a 2-screen setup.

My question is: How can we use the Unity launcher in MULTIPLE displays, but not all of them?

For example, the following shows three screens with the launcher enabled on all of them:

The only GUI setting I can use to modify this is "Launcher placement" but only allows selecting ONE display:

The end result I'm looking for is to turn OFF the launcher on the vertical (right-hand) screen, but keep them on the left-hand screens.