If you have enough fabric then go for it. Just remember to stop sewing 1/4" from the corner and anchor that end stitch by maybe backstitching there or stitching a couple of times in place.

Eleanor Burns shows a method where you iron the top border folded back to form the miter. Pin in place, then use clear thread and stitch it down. Some use a strip of fusible to hold it and some use elmers glue. If I had time I would find a video for you on how to do this. If you have time, go over to Quilt in a Day website and look for her video on how she does the mitered corner. It really is quite easy.