Traveled, by car, with my wife on a seven hour trip. She kept asking to stop at a restroom, but I could not accompany her to help her. Any advice?

You've already tried what I would have suggested. Only other thought is a lot of work, but may be a solution.

Medical facilities typically have unisex bathrooms, and in my experience they're cleaner than a lot of other public bathrooms. You could locate hospitals and medical complexes along your route, contact them beforehand to confirm that they do have unisex bathrooms, and go with your wife to help her.

I'm so sorry to learn of her loss of sight. You're both very strong and brave to find a way to continue with your travels after this event.

I would ask AAA for a triptik with family restrooms listed. You could also inquire with the highway department for each state you travel, they may send you maps.

Great idea that GardenArtist had suggested. If you go into a hospital, go to the main entrance [not the ER entrance] and ask at the front information desk if for the closest bathroom where you can help your wife.... or ask if someone could check to see if the ladies room is clear so that you and your wife can use it. Usually at the information desks are volunteers who are eager to help if you explain that your wife has difficulties in seeing.