The last time, I sewed it to the front, then pinned to the back and stitched in the ditch on the front. You just need to pin well (I pinned in the ditch to make sure it caught the backside). I was very happy with this method (which is the way my sister does hers) so I'm going to use it every time.
If there isn't enough to wrap around you can trim the seam allowance a tiny bit.