It's usually safe to change time zones if you observe a couple of precautions:

1. It's always safer if the game(s) are paused if your travels will result in changing the clock more than a few hours.
2. Never launch the game if the time on your computer's system clock is earlier than the timestamp on the savegame files. If you have to adjust time "backwards" at any point during your vacation, wait for the time on the computer's clock to be later than the savegame timestamps before you play the game again.

Have fun on vacation!