Fixes

I fixed the sky box.
I added more "clusters" of rocks.
I added sand texture to the edge of cliff.
Final Polycount of Cabin and KGA2:
Cabin Scene: ~20,000 Polys
KGA2: ~2,000 Polys

Total Prop poly count ~22,000 Polys

renders

Unity Goal Render

Render of goal

Quick Thumbnails

Unity Screenshot

Outside