Thanks folks!
Regarding the fog, if you have time later, I recommend Jasper Flick's distance fog tutorial:
https://catlikecoding.com/unity/tutorials/rendering/part-14/ to get around the "wall of fog" effect that depth fog creates. I used this in conjunction with some functions that bleed out colours based on a fragment's distance from the camera to simulate underwater Rayleigh scattering for Operation Apex. Sorry if you know all that already, happy to go into more detail if you like! It made a huge difference to have stuff rendered go cyan and then blue with distance.