I would recommend the optional French drains around the perimeter - a gravel filled trench, with or without a plastic perforated drain pipe in it depending on conditions and have it drain to the downhill side to daylight at about 1/4 inch per foot.
That could help eliminate any moisture that made it past the other defenses of the cabin.
Gophers etc. do not always recognize the trouble you went to to do your grading properly and will sometimes route their
water problems to your space.
A larger plastic umbrella can also help. Water wants to move down and spread horizontally also, so if it encounters your wall plastic then it goes straight down to the bottom of the wall and wants to come out at floor level - the place of least resistance.
A French drain or even a sump can catch that. I have a couple problem areas that I will eventually likely add a small sump to to eliminate the problem.
My house is in a very hard clay that water will not travel through with any speed, it stays like it is in a
bucket, so I have to consider other options. In deep sand soil that would not likely be a problem but then more side pressure on the walls could be a different problem. Each house and set of soil conditions is unique. I suggest that you become intimate with your soil and
land - learn it's properties to be used to your advantage.