Finally, I put a piece of 1/8 x1 x1/2 inch wide good quality ply on the inside front of the fusleage, and some light ply on the cowl side. I drilled the hole for the mounting screw, then put a piece of 1/4 inch hardwood triangle to fill the gap. Now, I put a small #4 washer between the triangle and the hole, so when I counter-sink the hole for the cap-head screw, it will rest against the washer that is inside and resist pulling through. I drill through again and then use a slightly larger bit to drill out the ply piece in the fuselage, mount the blind nut half way, then add a few drops of thick CA around the three prongs of the blind nut, then put the chin cowl on again and tighten up the screw all the way so the blind nut seats in the plywood plate. Done.