I wish I'd seen this post 6 minths ago since I've been working on the same thing, only I was using some boat portages across Lake Mead and Mojave to make gas stops reasonable. But you are way farther along and 200% more detailed than my "wing it, ride it and draw it method."
I will ride it and I'll pay for it too because I know the exhaustive work it takes to produce something of this magnitude. This is some of the last true remote desert here in the states that has a fair amount of abandonded roads from the pre-lake days.
Thanks for the heads up.