That’s a very nice piece of work Gregory 🙂
I’m sorry if I was a bit vague Jon. I’d inadvertently mentioned the dimension I often use for the width of the upper tier on shooting boards, but – in response to your question – a little extra width on the upper surface/platform can pay dividends when working wider/longer stock items and a secondary section (Without track for the plane) can be fashioned in the form of a bench hook and used to support materials extending beyond the main shooting board. I’d suggest making a larger shooting board (Length and width) as a potential future project. 😉
One of my larger shooting boards was made to carry guitar and cello sides/ribs, as well as sound boards and back plates when I used to make stringed instruments. It measures 4′ in length x 16″ in width, but was solely used for planing/shooting side elements square along the grain.