Best I can think of are these....
https://www.rei.com/rei-garage/product/123326/celestron-trekguide-digital-compass
The PITA is figuring out how to mount it and ensure the compass is accurate for your heading.
A lot of the current small GPS units have a combination of altimeter and sometimes barometers. Heck, even the Garmin watches like the Fenix have all of those things. Could make your own mount for one of those types of watches so you can wear while outdoors, take it off and dock it to a mount in the 4Runner.
Or... another option... bit more involving....
Most modern smartphones, the fitness tracker apps have compass, altitude, and temp/humidity. My shitty Samsung S4's app has those. Pick up an old used one online for cheap, shut off all the unnecessary bullshit and limit it to that app....
Convert Your Old Android Tablet into Beautiful Weather Station | Technical Tips
https://www.rei.com/rei-garage/product/123326/celestron-trekguide-digital-compass
The PITA is figuring out how to mount it and ensure the compass is accurate for your heading.
A lot of the current small GPS units have a combination of altimeter and sometimes barometers. Heck, even the Garmin watches like the Fenix have all of those things. Could make your own mount for one of those types of watches so you can wear while outdoors, take it off and dock it to a mount in the 4Runner.
Or... another option... bit more involving....
Most modern smartphones, the fitness tracker apps have compass, altitude, and temp/humidity. My shitty Samsung S4's app has those. Pick up an old used one online for cheap, shut off all the unnecessary bullshit and limit it to that app....
Convert Your Old Android Tablet into Beautiful Weather Station | Technical Tips