Hello @Robert913,
In the "Trip length" section under "Availability" click on the "Add a custom rule for seasons or specific dates" link.
Then cllick on the "During" box and choose "Specific dates".
Now set a start date and end date to cover the gap dates and set a minimum nights' stay in the "Minimum stay" box.
That will set the minimum stay for a checkin on each of those dates.
Regarding checkin and checkout on the same day do you have a checkin on the 24th of May? I see that it's unavailable on your calendar but there's no way to know from the calendar whether it's simply blocked or is unavailable due to a checkin. I just tried a booking for checkin on the 21st and checkout on the 24th of May and it shows that as possible.
Steve.