I have a TomTom which is next to worthless, but it keeps the DW happy as she can see how fast I'm driving.
On my side I use an Android tablet running Co-Pilot RV. Set your vehicle dimensions and it will pick routes based on that. I also run Waze for traffic alerts.
I consider these tactical tools for changes in route underway. The strategic planning takes place with Google Maps, Google Earth and the mountain guide.
I turn on terrain in maps and Google Earth has a route elevation profile feature that I use in the hills.