Paul,Just a word of caution.Being a full scale structural aircraft engineer for the last 30 years .I would not put a splice in any area for the wing cut out.This would be not a approved in full scale,due to the integrety of the joint.With a plane the size you are building I wouldn't trust it.Try and go with 48 inch material.If you do decide on the scarfe joint.Splice it at the front of the leading edge.Think it was point "B". Use a 4 to 1 ratio for the splice.and going forward Hope this will help you.