One about that size is all I've caught on the double fluke rig after fishing it a good bit. Even around bass schooling and busting on shad. They sure do look good dancing through the water. Lately I've been using a split shot just above the lower swivel to try and get them a few inches down into the water column instead of right on top.
Some guys have trouble on the double fluke rig Because the bait fish they're feeding on are smaller than a full size fluke. Try a fluke Jr or one of each. When I do it I've always only caught them on the smaller bait.
I rigged mine with the smaller swimming fluke jr in the front and the swimming super fluke in the rear. I think I'll go to both in the junior size. Now that I think about it, I've only caught one fish on the full size fluke and it was a jack. All the rest including my personal best bass were on the smaller ones.