I built the Elio with s3021, wing profile...
Not a problem with 1/8 x 3/8 basswood, top and bottom, over 100 tows with a hi start stretched to 18lbs
No pine block for wing tube carrier.
reinforced front and back with 1/16 ply...
Of course every ones experience is different..
google 'elio sailplane', there's lots of pictures..