If you want to go crazy, make bias binding and prepare to fold and stitch all the way around. I've seen larger hexagons done this way. I would make hexagons of a solid finishing color, stitch them onto it all the way around, then cut them off straight and bind it like any other quilt. Or....
You can trim the backing to the same shape and fold the seam allowance in on each hexagon and whip stitch.
You have the patience of Job!