I used to have a portable AC... Danby brand. I think it was 5,500 BTUs, but may have been a little larger. It had electric heat, too. The thing I didn't like about it was that it constantly blew air from the room out the vent. That means air had to come back in the room somehow... and that air was not air conditioned. Imagine running the central AC at home, but opening a window wide and putting a fan in the window pointing outdoors... not very efficient. A better design would have been a duplex hose that would have pulled air from outside over the condenser coils then back out -- no exchange of room air.
It was one of those annoying models that collected water in a tank. The tank was troublesome to get in and out, and cracked many times. I repaired it half a dozen times with
fiberglass mat. It worked, but it was a pain in the butt. Way too large for a
fiberglass trailer. Now, if it sat outside and just pumped cold air into a window or vent, that might be better.