You cannot count on the min and max values of the date field anyway, because the user can still pick any date via the date picker.
If you want to stick with a date field, Iād use the help property to display the possible dates and then use a hook that checks if the date is within the given range.
In case the alternative @jimbobrjames suggested (with a select or multi select) sounds like a good idea to you, Iād still not use a structure field to enter all possible dates but stick with the start and end dates and then use your own API (via a route) that returns a calculated array of dates between the start and end dates.