Interesting question. I’m also still learning a lot of stuff so I might not have the best answer, but I think what is of concern is mainly the number of vertices that are on screen.
So If it takes up half the view (even if its really far away), that should use more or less the number of vertices you use for a character, or any other mesh that’s near by, that takes up the same amount of screen space. Same goes for texture resolution I suppose.
Then as you get closer, you can use higher res LoD meshes, and unless you plan to go flying around the whole thing I think you could maybe get away with just adding more detail near the bottom of the nearest LoD mesh. Otherwise cutting it up into lots of pieces, each with their own LoDs is probably a good idea.
What I’m wondering about is how much of the mesh is still processed by draw calls if you’re only looking at a little piece of it…