Hi @Brant25
I think you are using the regular calendar to set the restrictions, not the Professional Tools multi-calendar, correct?
The best way to do it may be to block all days for check-in except Sunday, and also block all days for check-out except Sunday, but then make sure that you don't also have minimum stays (so set the overall minimum stay and all the minimum stays per day of the week to 1 night).
This should hopefully result in Sunday to Sunday bookings only, and no strange blocked dates on your calendar. But it's always important to go to the guest view and run some tests just to be sure it works out correctly.