Is it practical to use ground effect to extend range in an emergency?
When flying close to the ground, there is an important reduction of induced drag, the larger the closer to the ground one flies, so the airplane needs less engine thrust to keep a given airspeed. Anyone who has made a low pass over a long runway may attest this...

Flying in ground effect is a nice way to save fuel and extend the range. I remember reading that it was often used by carrier planes returning from a mission low in fuel...