I have a (second hand) Panasonic Toughpad that works ok for this. But lately I've just been using my Surface Pro 8 with a rugged cover on it. It may not be waterproof, but really, who cares in a regular vehicle. And with everything having an SSD these days, using it in a vehicle is no worry.
Navigation-wise, I usually run a mix of Google Maps (/spits in disgust), the built-in Mercedes GPS (when in the GLE), a Garmin GpsMap 62s, Gaia GPS and OziExplorer. With Samsung Dex I can run Gaia on the Surface Pro, and have it on a big screen, which works fairly well. Hopefully Android Subsystem for Windows becomes mature enough soon to directly run Gaia on the Surface Pro, but last time I tried it still crashed (and couldn't log in to my account either).