Well, I actually *want* the window blocked (the rest of it is filled with styrofoam sheets), as it's west-facing. I also have sunshades as an "awning" of sorts from below the fence top to the roof eaves, but anything that keeps the heat from getting into the room in the first place means less work for the A/C unit to do.
If I use ducts, I have to heavily insulate those, too, so heat doesn't leak into them and make even more work for the unit. Also have to make them leakproof to air at the joins. And I'd have to use ones large enough to block the window anyway, to keep the airflow high.
I had planned to do this sort of thing with the big unit I had before the fire (was stolen by the cleanup crew), but it's not worth the effort for the little one (at best, half the size of the big one).
Also, I actually like the noise, since generally I'm only using the unit at night when trying to sleep (I work during the day), and the dogs don't stay in my bedroom unless I'm there (or unless there's fireworks or storms or whatever, in which case Yogi often hides in there).
I *would* like to move the roof unit down to the ground to keep it out of the sun, and reduct it thru the wall rather than the roof, but that's not an option at all.
Best I've been able to do is cover the roof unit's exterior (except the exchanger/fan area) with layers of styrofoam, including the duct from ti's side down into the roof, and then also cover the ducts inside the attic the same way. This keeps as much heat from getting into the unit and thus the air, and so it does't have to work as hard. My brother keeps the circulation fan on all the time, so without the extra insulation, the air thru the ductwork heats up more and makes teh A/C come on much more often, and the farther rooms (like his) don't stay as cool. After I added the insulation to the roof unit, he actually had to turn the A/C up a couple degrees so it didn't chill his room down so much.