All 4 rubber stops rotate for me. Counter clockwise to get them out more.
The dealership, same one which fixed my vibrating mirror, had rotated them almost all the way out. I am pretty sure it was too much and it had minor effect on the trembling.
I actually undid their work, as it was obvious the stops bend below the hood, as there was not enough space for them to stay straight.
I am planning to find the right height by using a sheet of paper and finding the lowest height where the paper is held snug then rotating it an additional ~90 degrees out, to get a tight fitting.
However, I am doubtful this will have much impact on vibrations. I think it may only have a better damping effect, i.e. make vibrations subside quickly.
While many people report their hoods / mirrors are not vibrating and since all 4 different CX-5 vehicles I drove had obvious mirror shake, I find it difficult to reconcile, which makes me believe there are more shaking hoods / mirrors out there (of course, 4 is still a low number, so I could be mistaken).
I wish Mazda had engineered this obvious part better, it is right in the driver's view, perhaps with a light and stiff aluminum hood.