After cleaning the passenger side blister and treating with POR-15, I glasses in the bottom with 5 coats of cloth, let it set up and and lined the whole piece with 3/8″ closed cell coated rubber. 
That should be a dramatic improvement over the batt type insulation that was in there before, not only that, now the interior is waterproof and even if it holds water will be protected against any further rust. With this finished, I will begin work on the driver’s side piece, which will be a little more complicated because it has so many curves and the opening for the heater blower.
