Very good mod and good landscaping so far.
I generated landscape LOD in GECK (took about an hour) and objects LOD with FNVLODGen. There are some missing lod textures reported that you need to add.
<Note: textures\architecture\urban\ctandmonumentlod.dds diffuse texture not found, using replacement>
<Note: textures\architecture\urban\ctandmonumentlod_n.dds normal map not found, using flat replacement>
<Note: textures\architecture\urban\stonebldg02lod_n.dds normal map not found, using flat replacement>
If you don't have idea where are they used, press Ctrl+F3 in FNVEdit, enter _lod.nif in the filter box, then right click on any file and "Copy all to". This will copy all lod meshes into a separate folder of your choice where you can use file searching tools like WinGrep to find meshes by texture name inside them.
Here is SanFranMainWorld so far

The biggest problem right now is landscape and water LOD. Those issues on screenshot happen because you literally don't have heightmap in those cells under the water. You need to create the actual ocean basin heightmap, and make it much lower under the the water so it couldn't be seen unlike now on screenshot.
I also recommend to extend worldspace size and height map more to have LOD in the distance outside of playable space, not a small square that ends abruptly as it is now. Also make sure that all cells with water have "Has water" flag. In Skyrim's CK I could just draw a new larger border region around some map and it would create extra empty cells with water, then I delete region and cells remain. I used that to extend island worldspaces to have more water LOD. Not sure if it works in GECK, probably should work. I hope other experienced modders here could help you with that.
Check vanilla worldspace WastelandNV - it's heightmap is larger than the actual playable region just for the purpose of extra LOD.
Here is my generated LOD if you are interested
https://drive.google.com/open?id=0B4rR0C-Bcx_JX1FxSHVyNERVREU&authuser=0