Chuck,
Sorry to do this, but I feel inclined to play devil’s advocate. If I understand your track plan, you’re doing a turnback curve to have two mainline tracks on a 12” shelf, and you’re trying to conceal one of the tracks. Here’s some concerns:
1) Too much hidden track
2) Too little space on the remaining depth (after hiding the rear track) of the 12” shelf for reasonable scenery to get that open desert feel. Needs moar negative space.
3) Too many towns in the length mainline that you have. By the time you put in the passing sidings for all of those towns, you’ll feel like it’s practically a double track mainline with very short (less than train lengths) single track portions.
Sorry,
Debbie Downer