looking quite good, and nicely integrated.
are these hand-made?
from a technical point of view I think you should revise your LOD policy. reducing a mesh from 13k to 10k is not enough of a reduction to justify the cost of extra assets in memory. and then you butcher-slice it into a quarter of the polycount for the next LOD (I would bet the transition from 10k to 2.5k will look obvious)
a good practice is to roughly cut by half for every LOD. so 14k becomes 7k and then 3.5k