Okay, I played a bit more with this simple file I put up earlier, and added some things that have been dealt with on the forum before, but may help some of you. So, analyze and enjoy.
It's without the two 'assets', btw, so ignore any errors if you open up. And the water foam has been decreased in whiteness later, so that's why it's grey at front and pretty white further away. No compute terrain, so pretty fast, especially if you don't smooth the reflections.