Yes, that's the bridge. (Its been about 10 yrs since we were in Yellowstone)
I think she will be fine on most of these roads. Unfortunately for her, I like to take back roads to sightsee. One time outside of Las Vegas we took a day trip up into the mtns., The dirt road started out OK at the bottom, but half an hour latter we were on a one-way jeep trail, straight up on one side, straight down on the other, and only one lane. Even I was a little nervous on that stretch.
The neat thing was that at the bottom it was 75 degrees, near the top there was 2' of snow !!
Like me she loves scenic drives over back roads, so she had learned to suck it up in order to enjoy the views. She doesn't like the drive very much, but loves the scenery.
We all know the best places are off the beaten path.