I do have a large villa in Sicily that can accommodate 13 people. It is just outside the village of Scopello (45 min to Palermo airport). Ca 250 m to the beach. We do not yet have pool but planning permitting it may be there by August.
Feel free to take a look at: https://www.holidaylettings.co.uk/renta ... llo/226864
It is advertised for 10 online, but we can easily accommodate 13.
Contact me if you are interested in further information.