For the past couple of months, my sister-in-law and her husband have stored their trailer in our backyard. We do not mind; our backyard is not used often. I am not a trailer expert, but I know that their trailer is pretty nice. They use it mainly for storing lawn equipment and tools. At first, they never really used the trailer. It just sat in our yard. Then, a few weeks ago, my sister-in-law told me that they were planning on putting furniture in the trailer, so they could take it camping. I was quite confused. The trailer has no lights, no air conditioning, and no ventilation. How could they be planning to use it for camping? Apparently, though, they had it all figured out. The next day, they showed up with an air conditioning unit that they were going to install in the trailer. I have no idea what kind of air conditioning unit it was, but apparently, it provided both air conditioning, heating, and ventilation. The air conditioning unit did not use any ductwork, and it just sat on top of the roof of the trailer. I was flummoxed that it actually worked! I had never heard of putting air conditioning, or any sort of HVAC, in a trailer! The next thing they are doing is fully furnishing it and putting in shelving units. Of course, the trailer does not have indoor plumbing, but I guess if you are staying on a campground that provides bathrooms, that is not an issue. I still would not want to stay in that trailer, but I am glad that they want can!