Many years ago while recovering from two broken legs, I was driven in my car from the hospital to home about two hundred miles away. Roads were fine and the car rode well, but the bouncing and vibration of the car tended to cause me problems for quite a few miles until I got used to it (and took some p;ain pills). Your RV probably has a stiff ride and the travel may not be pleasant for her. The train sounds like a fun trip and she will be well taken care of, might be best for one of you to fly to Chicago and then accompany her to Denver on the train. Will cost more but should be worth it.