It is quiete simple....
select an aircondition with minimal noise. there are inside unit`s with about only 17db noise.
Choose a good place for the inside unit, that allow you, to install a gobo in front if needed, or build an exchange chamber for the fresh air inlet, which you can cool down easyly with an cheap aircondition.
my aircon is insralled since 2 day`s, and i am so happy for the cooling
before i had about 31