Oh, one suggestion I forgot to mention - since my lake was included as part of the sea channel, it received the same color treatment. The 15px stroke/50px blur turned out to be too much for it, and I ended up breaking it out into a separate layer with a 10px stroke & 20px (ish?) blur, though the exact values would depend mostly on the size of the lake itself. You might want to make a note of that - I noticed the sample map didn't include any lakes.