On my PA-18A and then PA-12 I had something like this velcroed to the interior wing panel. Ran the probe out and stuck to bottom of wing root fairing with RTV. Once a year changed the AAA battery.
Gary
Spruce wants something like 80 bucks for a darn through the window dial thermometer. Any ideas on another source that does not have the airplane word mark-up? I need a couple.
I prefer minimal distraction in the windows.....if I see something it want it to not be part of my plane and maybe another = see and avoid. Removing thermometers and replacing with something that's not blocking vision is why I went to the sensing units hung somewhere else. Plus spiders can find another home that way.
Gary