I use a variation of this approach. Make all windows exactly the same size (I'm using Hammerspoon). Hide applications (Cmd-H) instead of minimizing windows. Cmd-Tab to whatever app you want. Cmd-` to whatever window you want.
Sometimes the silly shadow around the top window gets too big, but then you can Option-Cmd-H to hide all other apps.
Sometimes the silly shadow around the top window gets too big, but then you can Option-Cmd-H to hide all other apps.