Big day yesterday, as I alluded…
First off, some more cleaning. I could see a pile of leaves, etc behind the windshield cowl, almost since i got the truck. They were compacted enough that my shop vac couldn’t extract them through the screen, so I had to pull the cowl. The wiper arms, and then six screws, and some maneuvering, and off it came. Here’s what awaited underneath:
Thankfully, being mostly dry or cold Alberta, this detritus was not holding moisture. So some more vacuuming, cleaning, scrubbing and scraping yielded this!
Much better! And since I had the cowl off, better address that blister under the windshield gasket. POR15 to the rescue! I’ll likely go after it more completely when I get my windshield replaced, but at least for now its AR-RUSTED. 
Okay, last vestiges of rust are now in front of me. The rockers. They ain’t horrible, and the main runs are solid, with just a surface patina, not holed. But the corners? Through the outer skin, both sides. Out comes the cutting wheel!
Did this on both sides, and then after some work with the flap disc, I slathered on my favorite miracle cure!
Much better! I will make some new rocker corners to put overtop, but for now I wanted to stop the oxidation in its tracks. While i was down there, I coated the entire underside of each rocker, end to end, which officially finishes my battle with the tin worm. Now its just a matter of making it pretty, with top coatings, etc.
As I’ve said before, the goal here is to make this thing last into the distant future. I believe I am heading in that direction now.