People that are stating that an AC will only cool to 20* lower than outside are not correct. The output of an AC should be 20* lower than incoming air to the AC measured at the AC. Otherwise you would never be able to cool the air less than outside air.
I had an very insulated 5er that was 35' in southern Oregon near Roseburg which can get very hot and the 5er had one 15K unit and it woud cool our trailer to a very comfy level. I'm not thin but in +90* temps our trailer would be in a 72* range and at night we had to shut the AC down a bunch to keep from freezing us out. The one AC was recommended by the President of the company who built out unit. He had the vent in the bedroom all wired for a second but he wanted us to try it first. This was a factory ordered unit.
Here is an article regarding the difference of air temps from incoming and outgoing air.
For some reason it won't let me post a direct link but it is from Motley RV Repair
Here is the link
http://www.motleyrvrepair.com/rv_air_conditioners_made_simple.htm