Early Barracuda body cracks under rear window

My '65 FS has body cracks under the rear window, and I've read here on FABO that they are a known problem. The body has been media blasted and each side is slightly cracked through the body lead at the seam there. I bought subframe connectors and plan on installing them in an effort to keep this from coming back, but my bodyman asked me to find out what others have done to repair the cracks. Any special tricks for a better repair than just filler and hoping that the subframe connectors fix the problem?