The longer the wings, the better. The key is that the wing provides lift for the whole aircraft, and the point of lift action should coincide with the center of gravity of the whole aircraft. Wings that are too long are easily affected by turbulence, resulting in unstable flight. U-2 is an extreme example. The U-2 shot down by the Soviet Union was "scraped" by the turbulence formed by Soviet pilots flying over the U-2 at high speed. The design of wings should refer to professional books, and aerodynamics is the basis. I suggest you have a look.