You can use a wall type unit that sets in a sleeve. Fedders makes em in 8 and 10 K.
I get em all the time for apt jobs where the wall sleeve is already in the wall.
You could install them in a window, they cost more though.
They slide right in and out of the sleeve.
United Refrig has em, special size like 24" x 14"
Hey cockroach, don't bug me! ©