I've managed to get my hands on a really nice window unit AC that can cool my entire living space (about 900 sq ft), but the downside of it being so powerful is that I either have to
leave it running on max, which gets the house too cold and uses too much electricity,
use its thermostat, which causes it to switch to just fan after the air gets cool enough, thereby re-humidifying the house. (This is problematic as the temperature setting needed to get the humidity to an acceptable level varies greatly by time-of-day and weather, and aside from eliminating extreme heat, removing humidity is my main reason for having an AC.) or,
keep manually switching it on and off based on temperature and humidity
What I'd like is to find or make a sensor-based switch I could put between the outlet and the plug to turn the unit fully on or off (not on or fan-only, where the latter actually makes the climate worse by re-introducing moisture) based on the humidity, rather than the temperature. Is there a product to do this, preferably something purely mechanical rather than over-priced electronics? I would think such a switching device would be a standard component in dehumidifiers, but I don't know what it's called or how to search for it.
Edit: Before commenting that this won't work, please be aware that the AC unit does not itself have any electronic controls that would misbehave when power is cut and restored. The control system is purely mechanical switches.