Vacation rentals and Air bnb need help with numbers

[Chou Yang]

I've come across a vacation property I might want to purchase. the seller is willing to finance with 20% down. we plan on using the property 3-4 weeks out of the whole year. My question is to those who use Airbnb, how many days of the month is your home currently being rented out? Approximately how much expenses do you incur for cleaning/mowing? I've calculated that with seller financing I would have a piti payment of $1500 month. The home can be rented out for $250 night. If I can rent it out for 15 days out of the month, gross rent would be $3750. Anyone with experience please help. Thank you