I don't see a special hazard in ditching in fog,
I do
No one would find you! maybe a long pole with a flag you could stick up through the fog and wave to passing ships before one ran over you
Serious though I had a nasty experience years ago with a jammed fuel selector and unforecast extensive fog.
Low on fuel I took to a military base who were colour code red and had a PAR, talked all the way down to an 80 foot cloud base and 400 vis
After that I tried to see whether it was possible to land in zero zero conditions using a radar alt for the flair.
Tried the experiment on an ILS in VMC with a safety pilot and yes I feel confident in an emergency its quite feasible using a rad alt in a Seneca Twin.
Pace