I have been programming since 1979 (yes 38 years) in multiple languages, for the last four years my focus has been GPS systems.
Assuming there are no GPS devices involved, things would be quite different from my previous bid, which was in error. The amount was wrong, my error.
What ever language you prefer for the code is fine with me, I do prefer Java, C++ or even PHP myself.
I would be using MySQL or pgSQL for data storage, and to handle the UTM zone enter/exit events, as both MySQL and pgSQL have geospatial functions built into them.
Please contact me so we can discuss the further, or if you have any questions.
Regards,
John H. Ward, Jr.