I, too, tend to raise the exposure with fog as it fits the mood of the subject. However, in doing so the light usually starts to look flat. Perhaps that is how it should be. Fog light is flat. But even in your underexposed image there is a ‘voluptuousness’ that a smooth transition of tonal range from high to low that has such aesthetic beauty. And no matter how much I try in postproduction I can’t seem to retain it when converting to a lighter image. This aesthetic beauty is really what make Adams work sing, especially with clouds.
I’ve decided that good fog images, like all subjects, is dependent on light. In my opinion side lighting is usually the best light for most sunlight images (because shadows are part of a composition). But with fog the optimum light is when the sun is behind it and passes through the fog. That causes the fog to glow and gives that rich range of tones.
https://community.naturephotographers.network/t/sentries/47912
vs
https://community.naturephotographers.network/t/obstacles/42410
I did try to process your image with my ideas but am not really happy with it. But I’m posting it because I think the composition is an improvement and could be useful to you.
One thing I would do with the fog index app is figure out where the sun will be with respect to the fog and drive to ahead of time to get the backward lighting when the sun is about the break through. In my image I just got lucky but this app could really up a success rate.