As I am still on patrol and want to install the mod after finishing it, I tested just a very little bit yet
I measured how far WEST I am from Greenwich (1625km, so drawed a 270° line from there) and what the difference of local time to GMT looks like (exactly 1h). I wanted to do this a little bit more to see by myself how reliable the local time is and if I could use that to get an idea of my current longitude.