you can always add binding to the sides, folding the ends under. stitch. then add binding to the top and bottom, folding ends under. no miters to do that way and it's just another way. I've done it on some quilts. just cut binding (I do 2 1/2 inch strips) a bit longer than the quilt side measurement. fold raw edges together, place along the edge of the quilt, pin in place, stitch (folding ends under) then fold to the back and hand sticth down or by machine. if by machine, pin from the front along the seam line catching the binding in the back.
then do the top and bottom binding.