Having had good results with experimentally wardriving (#2), I see that better software is necessary. Kismet on macOS is a non-starter, and I think it would be better in the long run to use a Raspberry Pi. (I'd be happy to hand that off to somebody else to stick in their car and drive around with for a few days — not so with my laptop.)
[x] set up a Raspberry Pi with a Linux distro
[x] install Kismet
[x] configure the Pi to use the USB WiFi receiver
[x] configure the Pi to use a second USB WiFi receiver
[x] configure the Pi to use gpsd
[x] configure Kismet
[x] set it to runlevel 3 (a GUI is unnecessary)
[ ] ensure that Kismet won't log anything other than SSIDs and their location (i.e., won't join networks)
[x] run Kismet, headless, on boot
[x] save an image of the configured SD card, to facilitate recovery or reproduction
[ ] create a deploy script that can be loaded via cURL and piped into Bash, so that somebody can trivially stand up a copy of this
Having had good results with experimentally wardriving (#2), I see that better software is necessary. Kismet on macOS is a non-starter, and I think it would be better in the long run to use a Raspberry Pi. (I'd be happy to hand that off to somebody else to stick in their car and drive around with for a few days — not so with my laptop.)
There are some good instructions here.