Shifting Sands

With the release of the Custodes I realized i had two to many metallic painted armies. I decided to give my Thousand Sons of the Silver Tower a repaint to the new "Sons of the Shifting Sands". A desert planet that's constantly shifting (very Tzeentch of me).  Think Tomb Kingish. Cities covered in the sands revealed everyday just to be buried, oceans flow and dry up.

This is a rough job, I need to figure you what color to paint the base rim, any recommendations? The base color is Zandri Dust.