Hi @Brandon1069
It would be easiest to message the host before you book. Explain the situation first, so that when you request the trip, the host can send you a "Special Offer" that is calculated according to the correct number of guests for the appropriate nights.
{Another way to do it would be to make two separate bookings in a row (one for 2 guests and one for 1 guest), but if the listing has a cleaning fee, this will then be charged between the two bookings. Also, some listings block a day after check-out, so you may not necessarily be able to book this way.}