When I made my Baby Snowmen quilt it called for a wider binding. You cut it 4" fold & press right side together; place raw edges ½" from raw edge of quilt; Use ¾" seam allowance, make sure edge of binding aligns with edge of presser foot. Fold binding to wrong side & hand stitch to back. I didn't even consider trying to miter the binding, just did top - bottom - side - side....
Yikes, my picture shows up so large, really only wanted to show you the binding to get an idea, sorry!