I have this set up using kmonad[1], and the following config. Many punctation marks are obviously missing, but I'm sure they could be added with a little thought. The mirrored layout is toggled by holding the space key.

    (defalias
      lhs (tap-next-release spc (layer-toggle ytrewq)))
    
    (deflayer ytrewq
      _    _    _    _    _    _    _    _    _    _    _    _    _    _    _    _
           bspc 0    9    8    7    6    _    _    _    _    _    _    _    _    _
           _    p    o    i    u    y    _    _    _    _    _    _    _         _
           ret  ;    l    k    j    h    _    _    _    _    _    _    _    _    _
           lsft /    .    ,    m    n    _    _    _    _    _    _         _    _
      _    _    _    _              _              _    _              _    _    _)

1. https://github.com/kmonad/kmonad