It seems that if I want to use a custom format for my Date field, I need to create a Formula field and use DATE_FORMAT(). Would it be preferable in most cases to offer a 'Custom' option in the 'Date format' menu in a Date field's settings? (see attachment) This would then show a text field where one could input the same formatting string one would give DATE_FORMAT(). That way I would not need to create a 'proxy' field to display the date as I prefer.