Server software:

traccar.org open source GPS tracking server

running modified 'traccar-web' UI to allow auto-login as guest on mobile devices:

traccar.litvak.su/installation.html

hostapd on Pi sets up the Wifi hotspot

dnsmasq on Raspberry pi acts as DNS and DHCP server for connected clients.

dnsmasq also catches all HTTP requests and redirects to localhost - end users just connect to the hostpot then browse to any (non-https) web address - good for catchy marketing! (e.g. hackadaytracker.com or any URL would work when connected to the Pi AP)

Apache2 on Pi gives some flexibility in redirecting http requests to localhost to our auto-logon guest URL

The off-the-shelf traccar.org tracking portal can accept our offline tilestache maps quite easily (need to define the custom map source in the Config section AND configure the user accounts to use the custom map source), but the litvak.su traccar-web mod required some butchering. See here for rough instructions (basically overwrite any reference to openstreetmap.org servers with your Pi tilestache server - editing the traccar.war file in ubuntu File Roller (archive manager) works quite well)

http://electron-tinker.blogspot.co.uk/2016/08/traccar-web-with-custom-offline-maps.html

Offline openstreetmap tiles are created with maperitive.com software and saved to the Pi

OSM tiles are served to Traccar viatilestache.org

Python code receives position and battery reports via the LoRa radio (For the HopeRf RFM98 lora module you have to adapt the DIO and SPI port definitions - instructions here:

http://electron-tinker.blogspot.co.uk/2016/08/raspberry-pi-lora-hoperf-python-code.html

, and reports to traccar software via OSMAND HTTP protocol (all done on loopback interface)