In RV Traveling Tales: Women's Journeys on the Open Road, Mary Campbell writes in "Stockbridge" about coming up to a overpass and not remembering the height of her rig! She backed up. Embarrassing, but she didn't lose any pieces.
You can read the article in Journal Pioneer. No photos, though. The couple was lucky.
If you can't remember the height of your RV, write it on a piece of paper and tape it somewhere in view of the driver's seat. And when in doubt, stop and go around. Jaimie Hall Bruzenak