I agree we could use an equivalent to port (originally larboard) and starboard. I happen to have BinderTek binders with holes on the short edge, including some for ledger-size paper.

The workarounds in Mirrored Margins with Landscape will do what you want, let you have a binding (hole) area on the long side. It takes some fiddling, which is part of the reason I recommend doing it using space-before and space-after formatting in custom Paragraph Styles rather than using TextBoxes or Frames.