Yeah, the stock navigation route planning is kind of weak. There are route planning apps that generally work better - ABetterRoutePlanner (ABRP) is one that most people seem to like. It isn't perfect, and still requires some tweaking. You mainly want to make sure that maximum charge is sane, and then add in amenity stops (meals and hotels with charging) in the appropriate spots.
What also works is if you are using ABRP on your phone, and once you have a route you like, share it with 'maps' - that transfers the route to Google Maps if you are using Android, and if you are using Android Auto, it will show you the route with the stops on the car screen.
I believe if you have iPhone, you can do something similar, but I don't have iPhone, so I can't give any details.