All 2x3s are in place for supporting the custom plywood floor. Only two of them are bolted to the seat anchors in the floor---bolts are visible in slots cut in the first (rearmost) and third 2x3s. The others 2x3s merely lie atop the carpeting. Masking tape was used to establish temporary alignment marks. The empty seat well was covered with lids that acted as part of the floor. Those lids required something to hold them up, so I built a plywood box for the well that acted as a lid support.