I also live in the west so I am frequently out of cell range where I travel. As others have said, the first thing is keep your coach maintained but things can still happen. I did have a problem once east of Cheyanne, WY. Coach was on the side of the road and so I started to walk. I didn't make it more than 50 yards before a car stopped and took me to a tiny service facility where I got the help I needed.
As was said earlier, we survived very well without cell phones before and can survive without them now. We are just used to them and the convenience that they bring.