OK! Now the panes are tiny and silly, but we can help them, temporarily at least, by zooming the current pane to fill up the entire window.
Type <Prefix>, z (zoom the pane), and you'll see the pane zoom to take up the entire window. If you look at the status bar for the current window, you will see a Z added after the asterisk (*) to indicate that the window is currently filled with a zoomed pane.
When you are done operating on this zoomed pane, the same command <Prefix>, z will zoom it out back to its normal place in the window.