On the 737-800 I'm taking from IND to LAS, seat row 15 only has two seats on each side of the aisle, whereas the other rows have three. The window seats are missing in row 15.

If you are in a window seat in row 16, immediately behind the missing seat, will the flight attendants let you place a carry-on item on the floor in that blank floor space where the seat is missing? (I mean a small personal carry-on item that you would normally place under the seat in front of you.)