If you have a Google account (like Gmail), on your computer or laptop, go to Google Maps and sign in. Then go to My Maps and you can import the .gpx file. Get the Google Maps App on your phone and you can pull up what you just imported.
Having said all that, I would rather use the RV Life app and it's included RV Safe routing. Works similar to RV Trip Wizard in that you enter your RV dimensions, etc. and the routing logic keeps you safe. You can also just access your static saved RVTW trips.
Tom, Kathy & 2 Goldendoodles, Sandy & Lucy
2019 Newmar Ventana LE 3412, Freightliner XCR, Cummins ISB6.7, 2014 Honda CR-V FWD