The most common way to figure wing area is to add the root chord to the tip chord then multiply that by the distance from the fuselage side to the last rib. If you include the fuselage area the number may not even be close, for example my heilo stallion has a wing chord of 16-inches and the fuse is 11 inches wide thats 176 square inches that doesn't lift anything. If I used the SAME WING PANELS on a fuselage only 5 inches wide would I have less wing area?