I disagree about dispensing with the Real Time Clock. (1) Most Arduinos have a cheap resonator instead of a crystal which do not allow good timekeeping. Even the ones with a crystal are not very good. (2) An Arduino will need to have the time reset after a power failure whereas an RTC will have a backup battery. A DS3231 for example even has a crystal temperature and age compensation mechanism.
Also with automatic daylight saving time compensation, whereas a manual solution would be easy to implement, someone has to be there at maybe 02:00 or 03:00 (depending on the timezone) to operate it.