If built faithfully to plans, reducing the plans usually results in an overbuilt plane that is needlessly heavy. Consider reducing the number of wing ribs and maybe using an open bay wing structure instead of a D-tube design with cap strips and shear webs.
Remember that not only is the plane lighter, but also it has a smaller wingspan, which reduces bending stress on the center of the wing by itself. The compounding of these two factors means that you can get away with flimsy wing structures that you would never get away with on the larger plane. Unsheeted foam wings are plenty strong for a typical 1/2A size plane.