Not for RV-specific gas stations. But truck stops like Love’s/Pilot’s, Buccee’s, etc are usually pretty safe bets to be compatible with your motorhome/trailer. And I know for sure Love’s has an app.
No RV specific apps, but Open Roads app (for diesel) and Gas Buddy are helpful. Plus, here’s a little tip, open the gas station in Google Maps satellite view to see the layout and to get a good idea if you’ll fit. Their “street view” also helps!