Nice job on the mock up. You may want to reconsider the toe kick. It'll be a real B!tch to clean under there and might be conducive to mildew, not to mention baits finding there way under there - out of sight out of mind. Nothing like week old baits stinking up the place.
Got a ? for you..maybe my eyes aren't as good as I thought they were, but it looks like a cutout at the transom bottom where your new transom is joined to the outer skin where the drain plug would be...You doing something special there or will it be filled later?