Yesterday I finished screwing the boot floor OS  perimeter rail in place.  Today was spent finishing the joints to ensure the side pillars line up correctly for the cladding panels and packing any gaps in the joints.  Late afternoon today I removed the rearmost boot floorboard as it is rotten all the way across.  This gave me access to the top of the chassis at this point, where a lot of corrosion growth was evident between the insulator and the boot floor support.   I removed the insulator and the corrosion growth and treated the chassis top surface with Vactan.