APUs are WAY overpriced, and therefore economically NOT practical.
Here's what I do:
In summer: I run the A/C for 1/2-3/4 hour before I go to bed. If I wake up hot/sweaty at some point, I turn my 12V fan on & go back to sleep. If I wake up hot again (usually don't), I run the A/C for maybe 1/2 hour tops, & go back to sleep for the rest of the night.
In winter: I have a generator (around 2500W) connected to a small heater that I run on LOW setting, when the forecast low is to be 20-40 degrees F. If the low is to be less than 20 degrees F, I run the truck engine for heat. Which I virtually NEVER have to do running FL and coastal GA.