If they don't hang outside the window they'd have to hang inside the window, and would need a more complicated ventilation system to take air from outside, heat it up and vent it back outside. At that point you'd have a window mounted two hose AC anyway.

So yes, your next best option is going to be a two hose portable AC. One hose takes air from the outside to cool the condenser, one hose to throw that hot air outside.

Single hose works too, but they're less efficient because they take cold inside air, cool the condenser and vents it outside, which waste some of the air it just cooled for that and it creates negative air pressure inside which will bring hot air from the outside to replace it from any cracks and holes in the house.