You could install a heat sensor in the stove, and a pipe above it: whenever the temperature was something, water would come out of the pipe. With enough data on the properties of the stove and its stones, you could have absolute temperature and humidity control!
(Wait, no, doesn’t sound good. Not many maniacs or supervillains have gone for absolute temperature and humidity control!)
Better still, you could install a microphone and program a computer to do speech recognition. Pick ten random words, and shoot water on the stove when one is said. Then choose a new random word for that spot.
And if there is a minute of silence, water!
And always water for “Aaah!” and “Hot!” and “Stahp!”
Come to think of it, this is almost a sport already.
Or, since a sauna stove takes hours to warm up with the traditional wood-burning, you could replace the burner with an afterburner — with a whole jet engine. I’m sure you can find them for cheap somewhere. Just don’t keep it on for too long or the stove melts.
And be sure to make sure your stove is well attached to the floor. Otherwise seven miles away your neighbor is going to have a nasty surprise.
“Hallo? Police? Some… somebody just threw a sauna stove through my window. My second-floor window. No, officer, I haven’t been drinking—”
Also, make sure the floor is attached to the ground.
“Hallo? Police? I wish to report what I think was an aircraft accident. Apparently it hit a sauna up there at seven miles, and— Hallo? I have the thing on my patio, officer, ceiling beams and all!”
(This has been another proud production of me, dad, sauna and too much imagination.)