@Zheng49 I've had guests who have traveled to other places, including camping, who have politely asked if they could do washing when they have stayed for 1 or 2 nights.
None of us should ever assume.
@Thainara4 Include in your listing that a washing machine "may" be available if it is.
Women tend to need to wash personals as may those who have medical matters like Incontinence which are sensitive personal matters so always be respectful.