athenascooter

my laq had me add fabric to each end so it would fit on the machine and it worked Very little was shown and it was covered by the binding

ukdame

I am no pro quilter by any means but if you sandwich the top then batting and bottom fabrics together then use a binding for the edges ( it could be a coordinating fabric) then both pieces being the same size should not be a real problem. I like to use my bottom fabric as a binding so have to remember to cut it larger.

My time

If your don't mind your quilt being a tad smaller why don't you just go ahead and quilt it and see what happens? Then when your done just trim it.

Bubbie

I would add a border on the back, make it different than the rest of the backing. It will look as if this is what you wanted all along (did it my self once or twice - don't tell).
So far your runner is wonderful, you do very nice work.