I just found a newer Android app for navigation that seems pretty interesting. It uses premium HERE maps (just like Garmin) and allows for offline saving of the maps. You can set your vehicle parameters to take length, weight and propane route restrictions into account. The most interesting setting is that you can bypass "truck route" restrictions while still being routed based on vehicle size and weight. That seems perfect for an RV.
This does cost money which is understandable since it's HERE maps. But you can see the calculated route and the ETA in detail without paying. I've been playing around with various routes tonight and it seems to do really well. You can't actually navigate a route though without paying a subscription.
I have no relationship to this company whatsoever.
Here is the link:
Google Play Store link
2011 Born Free 22' Class C Rear Side Kitchen