I used a thin strip of 0.024" alclad to fabricate a striker plate for the camlocs: I riveted this to the inside surface of the cowling to protect the cowling fiberglass.
Next, I drew the camloc button holes in the oil door's upper panel, clamped the camlocs in place, and matchdrilled the rivet holes. After several alignment checks, I drilled the camloc button holes.