Hello,
From 2005, I worked on GPS Tracking System from single app to more appealing Enterprise grade system.
Speaking about technology stack itself, I actually used PHP-MySQL based for the first long time agi, can give you more much better options with NodeJS-PostgreSQL stack if I may give suggestion. It will give you real realtime GPS tracking system instead of AJAX (periodic timing update, usually by 1-5 seconds) that will throw unnecessary resources.
Would be great if we can discuss more details about your project, and I can give more samples of my work.
Thank you and looking forward to hearing back from you.
Regards,
Erick