I've an an eye out unsuccessfully for a long time to find a good simple thermometer. That I could strategically mount, preferably an analog not electronic or digital, that could be mounted someplace visible form the helm.
I never thought about an altimeter.... I guess not that big a deal for me since 98% of our Rving is done in Florida at 50 Ft or less above SL.
reminds me though of a story though...
Happened a long time ago, while I was knee deep into studying and practicing for my instrument pilot's rating (I'm a private pilot). Well I was basically immersed with the subject. When not working I would spend nearly every waking moment reading, practicing, or just thinking about it.
Anyway, one morning on the way into work..... or maybe it was on the drive home... it was that long ago... anyway it started raining so hard that visibility dropped to nearly zero. I could barely see past the front bumper. Like a reflex I started glancing down into the 'cockpit'. Took me a second to figure out that I was fighting the urge to go on instruments! I was looking for my directional gyro, altimeter, and other instruments!!!
Good think this was before all the fancy moving map GPS's and other things the cars have now days, or I might have done it!