Chevy, I built a Mustang like you describe and it is my favorite 1/2A plane. I used the 24" Guillows plan as a guideline, but narrowed the fuselage as much as possible. It has 120 sq inches and weighs about 11 ozs. Oh ya...the wing is a solid sheet of 1/4" balsa with a full depth spruce spar that is about 3/16"x1/4"x12", and a little fiberglass in the middle 4 inches of the wing, IIRC.