Hammerspoon is the only utility that could give me what I wanted: Window columns sized ⅓ ⅔ on the left monitor, and ⅔ ⅓ on the right monitor.
Hammerspoon is the only utility that could give me what I wanted: Window columns sized ⅓ ⅔ on the left monitor, and ⅔ ⅓ on the right monitor.