I decided to put this in a blog - 3rd plan (Plan check& plan check 2.2) are the earlier versions.

Thank you for the feedback! After mulling over your ideas I decided to get rid of the return loops and go twice around the room. So here are more details

HO scale std gauge California/Nevada desert / mountain mining shortline, late 1950's steam

Continuous running - Single operator

2%-2.5% grade Short trains 6-8(10?) cars

Original idea for branch( based on Tecopa Railroad). 4%+ grade-push empties up, back loads down

I'm getting ready to start a  real layout and use homosote spline. My question is how tight of a radius will it bend? I will be having a few 20" curves