Yea, I agree with looking for someone who does this often. The reason being is you're going to have to get into a lot of areas where you'll be close to them to find them. You won't see them just moving about...it will always be in some sort of crevice or underneath a rock. They will sun bath in the morning and late evening as was said, but they blend in so well that you might not even notice them. I kind of disagree with the gentleman who said you would have a hard time finding them in Mojave. As a matter of fact, one of the more notorious snakes in that area that has traveled into some of the nearby towns is called the Mojave rattler. It's a generic name, but there out there. It's been said a million times and you know this for sure, but be careful! The speed of these animals' strike is never fully understood until you've seen it in person...it's best to see it from about 15 feet back!
--Joe
P.S. If you want to find some rattle snakes, get into some of the various foothills in California and search to about 3-5,000 feet in elevation. Tons of food, lots of places to hide and these guys are rampant in those parts.