We broke down and bought a room air conditioner for it today. 5200 BTU, and an electronic thermostat which shuts down both the compressor and the fan when the setpoint is reached, for $219. Even has a remote control, not that I'll get much use out of that.
Unfortunately, installing it is proving to be nontrivial. There are two problems, both related to the storm window over the window I need to install the unit in. First, the lower panel of the storm window is stuck. I haven't been able to raise it enough to clear the unit, and I tried about every trick I could think of with just muscle power. The other problem is that the storm window frame is tall enough that I need to add spacers to raise the A/C so that it can tilt outward slightly, as is needed to keep the condensate dripping outside rather than inside.
The first problem is probably solvable with the application of sufficient force, and the second merely requires a couple of 2x2s. Unfortunately, that means Monday at the earliest, since there's no place to buy lumber in Fairmont on a Sunday (or even a Saturday afternoon).