You might find the background you have been thinking of by checking out photo locations using railphotos.net and limiting the search to Union Pacific and the state of Nevada. A second search for Union Pacific in California with the keyword "Cima" might also help to find your spot.
There are some great photo locations between Milford and Las Vegas, but it's a one-shot deal for the 4014 (except in Meadow Valley Wash near Caliente). However, you could spend the day and get some good contemporary UPRR photos, along with the 4014, but that country is a destination, and a rugged one. You will never again catch the train until is is at Las Vegas. You have to go in on "graded" roads that drop through dry washes where you might find deep sand. And there is no cellular service nor is there anybody out there to rescue you. If you want a photo out there in the red rock country east of Las Vegas, you ought to make a dry run in advance so you can find the particular rabbit trail that takes you where you want to be and find out if there are any locked gates in your way. And be sure to let someone responsible know where you are going, so they can call the Sheriff if you don't check back in with them after 24 hours.
One thing about it, there are no annoying trees to block your view, but you still have to find the track. I'd suggest DeLorme map books of Nevada and Southern California.
I don't think that's what you had in mind, though, is it? West of Las Vegas you may find something more like what you want. Just be sure to carry plenty of drinking water and review in advance how to find the place that they put the jack if you are driving a modern day vehicle. An Army surplus entrenchment tool and a little bit of scrap wood is often handy when driving on graded roads in the desert.
I spent 9 years in the Mojave Desert as a Santa Fe official. Proper preparation prevents getting stuck.
Take the Toyota pickup. Leave the Accord sedan at home. If you go early and set up just the right photo, be prepared for there to be a cavalcade of cars at any location where there is easy access. Also don't be surprised if, after you have arrived early and set everything up to get your perfect photo, several people in dune buggies or jacked-up Jeeps race in at the last minute, raising lots of dust and possibly blocking your perfect photo.