That is exactly what I was thinking I would do- jack the corner up, get some blocking in and address the drainage issue.
The camp was built on a slope, with the front of the building near the higher end of the slope. The corner in question is on the front. The road is above grade from the building and I think water runoff from the road along with the roof are causing these issues. My grandfather put french drains in to divert water from the road around the both sides of the building, but that was 50 years ago and they probably are plugged up by now. Once the corner is back up to level, I would definitely put in new drains and probably gutters too.
The problem is my old man is getting well old and not very enthused about doing the work. We have a deck that wraps around the building above this area which makes it difficult to work. We would need to remove some of the deck. I am not sure how deep the previous footers were dug, but I am thinking this is something that would be much easier with machinery since there isnt much space to shovel with.
If I cant find someone who is capable and willing to do the work for a somewhat reasonable price, I will find a way to get it done.