I've been creating a floating city, and because of its size I've been having to put a lot of 'is LOD' checks on a lot of mountain pieces. So many pieces marked with LOD that I wouldn't be too surprised if the game explodes at any moment.

Yet, this time-bomb problem of mine could be fixed if I could create actual landscape instead of using 1,001 mountain pieces. So, is it possible to create a second 'land plane' that isn't at typical ground level, in a pre-existing area?

Short answer: No. :/

This makes me one sad chicken.