The sun rises East by North East around 6:20 am and sets West by North West about 7:30 pm.
Interestingly the 4:30 street points North, not the 6:00 street.
What direction should my tent be set up facing?
The Answer is: It doesn't matter! Assuming you have a No Bake Tent you can set it up facing any direction and it will work great. We prefer to set up our tents with the front door and front vestibule pointing North when it's convenient. We also like to put our cooler inside the vestibule to keep it out of the sun and keep the ice ice longer (Yes, this makes a difference).
If you have a normal tent try to set up in the shade of a RV, under a shade structure, or next to a box truck that blocks the Sun to the East of your tent.
If you're setting up a shade structure the first priority is minimizing South facing Sun. Because the Black Rock Desert is at about 40º North Latitude and it's late August the Sun only reaches a peak altitude of 58º above the horizon. So a lot of light will get in under you shade structure. Late afternoons around 3-5 pm feature the hottest temperatures of the day so you might want to bias your shade towards keeping cool in the afternoon. The sun is also at a lower angle early and late in the day - so a bit of extra shade cloth hanging off your shade structure on the East and West sides will help you stay cool when you're not in your tent.
Solar Panels should be set to an angle of about 35-40º (from horizontal, 37º is considered optimal). Early morning light is filtered through more atmosphere and delivers less power to your panels. As the sun gets higher in the sky you will get more power - picking an angle that maximizes the time the panels are closer to perpendicular to the sun will result in more power to your batteries.