I’ve made a tracing paper model of a placket closing from a 1953 pattern and a sample in muslin. I know the design could use improvement. Constance Talbot’s 1943 book, The Complete Book of Sewing offers more detail. I think the clipping at the end of the placket (shown below) may be necessary. Both the underlap and the overlap could be wider. I will definitely sew the side seam first, ending at the placket marked by tailors’ tacks. In order to eliminate bulk I might not turn under the raw edge of the overlapping bias strip. Will also consider hooks and eyes; hooks and buttonholed thread loops or bars; or even buttonholes and flat buttons rather than snaps. If the fabric is thin, as the muslin is, underlining the pattern piece may be necessary. The search continues for the perfect placket.