I think this is indeed a keeper for working on. There's a lot you can do with this pov!
I've checked your tgd and I'm surprised at the settings. Somehow when looking at your render I think the settings could be improved, but they all look fine, so I'm a bit confused why it doesn't turn out as expected.
What kind of compression do you use and how much?
I noticed a nice possibility for rendertime optimisation. You can reduce your lake-size to 300m when you position it in the middle of your POV. That will save you quite some rendertime and more possibilities to crank up other settings

I'll try to make an iteration of your tgd and post it here.
Cheers,
Martin