If you're a Roadtrippers Plus member, you can select route avoidance preferences or enter your RV safety details in the mobile app by following the steps here: How to Set Up Routing Options
Currently, trip routes cannot be modified within the app by dragging and dropping the route to create via waypoints. This is mostly because the route we show doesn't necessarily mean it's the route your navigation app will suggest. Waze or Google Maps may choose a different, efficient route for you to follow. If you use our in-app navigation in the Roadtrippers app rather than another navigation app, the navigation should stay very close to your trip's route.
The best way to modify your route is to go to Roadtrippers.com and create or edit your trip there. You can find instructions for customizing your route on the desktop site here: Quickly Customize a Trip's Route
After modifying the route, go to the trip's itinerary then click the Directions button. The directions shown there will be the directions needed to follow your custom route on the map. The directions can be printed or saved as a PDF if your computer supports it.