Thanks everyone for your support and encouragement!
Travelnutz:
You have a very extensive list of camper hardening protocol! However, everything you detail I think is absolutely necessary to implement when the camper is new (as you have done) if you want to be sure of longevity! I wish I had done the swap out of screws completely way back at the beginning.
Sabconsulting:
I thought hard about leaving a few "sacrificial screws" in as "scientific instruments" for periodic extraction and analysis, however, I created a "map" of the problem areas (there were very specific sections along which screws in catastrophic condition were extracted), and these areas were: the trim under the fridge, under the battery compartment and under the propane containment insert.
Hardening the 2 compartments the way I did I am sure completely eliminated (for perhaps 3~5 years) those intrusion routes; now the fridge is another story. A tin tray lays under the fridge in contact with the wing wood, but that area was rot-free (thanks to a large ~1.5 inch diameter vent hole with screen drilled into the under-wing wood by the manufacturer under fridge, which I will implement under the battery compartment this week!). So, I deduce that a small quantity of incoming rain (through fridge vents) collects on that tin surface, and flows outward to the camper aluminum frame member, where it finds its way into the aluminum frame tube through the near-by butt joint (the aluminum tubes aren't welded all the way around their 4 seams -- at least on all the tubes I have "uncovered" ). I may try and "inject" a non-volatile foam inside the tube member (via the screw holes under the trim)...but have not decided as yet.
