Pam, I would not try any stenciling on this quilt. It really is quite stunning and Judi did a show-worthy job of quilting it. I say enter it in any show you like. A smaller local show will certainly win you ribbons and a big juried show like AQS, well they nitpick everything but so what. There is nothing more exciting than seeing one of your own quilts to hang in a show. If you truly have your heart set on winning a ribbon with it (and a little cash) enter it in your county fair. I can pretty much guarantee it will win something. Because AQS is a juried show and you have to submit photos, submit a photo where you can see the shadowing. I wouldn't mention anything on the entry form. If the judges notice it and think it deters too much from the show-worthiness of the quilt, (which I really doubt) the worst that can happen is they won't accept your quilt for entry.
If you feel you must do something, I really liked your prairie point type idea with the matching border fabric. That picture you posted was really pretty enhancement. You could lay a bunch of those out before actually sewing them to know for sure if you wanted to do that or not.