Here are the pics of what is the worst damage to the siding. I'd say that 10-15% of this board is corroded away. (Please forgive the weeds.) This is the front wall of the house below the front porch where the foundation only goes to grade.
The porch (and part of my bedroom) sits above an unfinished crawlspace with a dirt floor... its the 'Silence of the Lambs' portion of my basement. I'm not super concerned about moisture there. I may have a sump installed in that space someday, but for now, I just let it be.