I am not saying that it is mandatory but I did not want to put A/C through the roof of my
Casita b/c of my garage height. I did want to take advantage of a cheap window unit. The factory unit in the
Casita died and the concept of having it sit on the floor in front with no ventilation was stupid anyway.....extremely inefficent with crappy airflow. You can stick a small unit through the fire
escape window in the
Casita. I built a wood frame against the
fiberglass as the support because the
fiberglass is not strong enough to carry the
weight. I also put a long 2x4 under the A/C on the outside for support so the condensation goes outside and the fins are well ventilated......I made sure the A/C was hanging on the wood frame and not the
fiberglass. I cut small panels to be sure that the area was sealed. It worked great in the middle of summer in the Mojave desert two years ago. It was a small A/C from Wal Mart and I was able to fire it up with a Honda
generator. I know you need to match the
generator to the size of the A/C. Of course nights in the desert are not that bad and it is not humid so I did not really use it much at night but midday with 118 outside it was fantastic. But it is a lot better than the factory unit because the airflow is high up, not in the closet and the outside airflow makes it quite efficent. Now I also have a nice storage locker in the front of the trailer below the closet. When I travel I take the A/C out and since it is so
light weight I can carry it easily and I stick it in the front locker. When I set up I just install it and the frame and all and it takes about 15 minutes. Another possibility, that I suppose one could do if one did not want to take it out for travel would be to cut a hole in the back or stick it out the back window. But you have to have the A/C coils outside........otherwise I have seen it ruin the floor of RVs. I have a picture but unfortunately it is on my phone....but it is pretty intuitive.....and the small wal mart A/C units do fit with plenty of space to spare. They rotate the models but they always have one for about 119 dollars.....or did up to two years ago. And the fire
escape issue might make it a poor idea for many people.....so I am only describing what I did and not saying it is an ideal solution. But I slept in the front bunk and I had the gas turned off and the
generator was in front of the tow vehicle for noise control. And I never used it through the night because the desert does cool down by 11 PM or so.