Another mod I'm glad I did was to make the floor cleats on bulkheads 2 and 8 twice as thick as called for so that they stand out from those bulkheads more. This made screwing in the ends of the floorboards much easier. Otherwise the screws are very close to the ends of the floorboards (too close in my opinion). I made those cleats 1 1/2" instead of 3/4". I made them a little thicker in the vertical dimension as well.
Bob