Same issue as you. Second floor bedroom above the garage gets really hot, but we can't stick a window unit out the front of the house because it would be conspicuous, ugly, and prohibited by HOA.
What I do have is access to the attic part that is adjacent to that room. So what I'm thinking of doing is punching a hole thru the drywall of the bedroom into the attic, mounting a window type AC unit in there so the attic is the "waste heat" side. I would install a drip tray to handle the condensation, and maybe something else to vent additional moisture and heat out of the attic. They make solar powered fans you can install that pull air out the top of the roof.