This is a little late but I'll tell you how I did my 46"=x49" hexagon quilt (each hexagon 1 1/4" across parallel lines)
Quilt the piece first. The make a ring of hexagons indentical in size to the ourter ring of the quilt top ( or mirror image if the sides are irregular)
then match it on the back and turn under the edges and whip stitch them closed witi tiny stitches -joining the outer edges and then stitch the inner edge to the quilt top.
As, I said I did this on my quilt and it was accepted at the International Quilt Festival last year.
I've tried to attach a photo of it but I apologize cause I've no idea if I succeeded. j