I have exactly this setup. My left monitor is portrait, showing my 109 lines of code at a time, 119 characters on a line. If I ever have to deal with longer lines a keyboard shortcut moves the terminal window to the landscape monitor and VIM automatically resizes the content.

Is it? When I've tried that, I've found it impossible to do without placing some, perhaps most, of the panel above my eyeline, which is a recipe for neck pain.

It is not. It is too thin. I have done it.

It is also too thin to read comic books. Wasted space at the bottom.