My design was to place carriage bolts down through the floor, beams, undercoat and through the holes in HF trailer beams. Split washers, then wingnuts will keep it connected.
I had to drill one layer at a time and then align them all. You see the floor being glued to the floorbeams.
Both parts are drying. I added the 14 gauge wire through the floor beams for the floor outlets to be.