Honestly I wouldn't risk the Gerlach post office - not because of any issues with the US postal service but because the post office may not be open when you arrive.
A much safer option, if the art will fit in a car, is to pick a hotel in Reno where you plan to spend a night and send it to arrive about 2-3 days before you get there. (I do something similar for many of my conventions). Hotels are well-accustomed top this sort of thing, some charge $10 or so to receive the package, others charge nothing. JUst label your package "John Smith, guest arriving Aug 22, ABC Hotel, 123 Maint St, Reno, NV".