With quicksilver my rear bedroom is quite a bit larger than 72x80. And one Goldstar 5,000 BTU will reduce temps from the mid nineties and 75% R/H to mid seventies and 60% R/H. When I'm sleeping the toilet paper just has to endure somehow as do the canned peas and sofa cushions. likewise in the afternoon, the bed mattress has to suffer when I am not in the bedroom. I have four 5K Goldstar units.
Sweating and swearing while on the road, the voltage cannot maintain a 13.5K unit. Most of the time I cannot hear the neighbors curse me out. The Goldstars are 10.7 EER. They cost $42.95 each at Fry's Electronics in 1997. The price is not a misprint.