One way could be to move to Sweden.
Here we write dates in the sensible way as 2013-08-12. Also known as ISO date format.
Other than that I would recommend that you use the date fields already present in calibre, but change them to only show what you want them to show.
More about different ways to change date handling in calibre can be found in this recent thread.
https://www.mobileread.com/forums/sho...d.php?t=219838