A suggestion, could you create distant mountain meshes (with distant trees) so when viewing from windows such as chorrol or bruma it makes the scenery more immersive?
Someone please correct me if I'm wrong, but LODs are impossible to create in interior cells. Also, due to a lack of texture blending and other various landscape-related issues stated in previous posts, the landscape is extremely difficult to do.. You could try including normal mountain shaped meshes and placing them in the distance (I think), but for many people the object slider wouldn't be far enough to allow vision of said meshes. Another solution is adding a panoramic flat mesh with a fake distant landscape image displayed on it, but that would not allow you see the weather, therefore rendering Weather-All Natural's indoor weather feature useless. I hope the information I posted was accurate and sufficient enough. If you need more information, try looking at some of the previous posts in this thread.