Re: Fog machine in bass drum.
Sounds cool, but I'm not sure that would be a wise move, for a number of reasons:
The "fog" in a fog machine is not water, so it wouldn't be a matter of your shells getting warped from water vapor. More often than not, it's a chemical solution which is heated to form the fog. I would be more worried about the chemicals in the fog solution messing up the adhesives, the wrap on your shells, and on your hardware.
The fog solution is supposed to be non-toxic, but concentrating that in the typical space of, say, 22 x 18" (your bass drum shell), could make your breathing a bit dicey to boot.
And, as you hit upon in your original post, the machine itself "takes up a good amount of real estate" inside the drum, and, like anything else, it's gonna affect the way the drum sounds. I would experiment with something about the same size of the machine and see how it affects the sound before goin' for the fog machine.
Experiment with it, though, and let us know how it works! Good luck!
keep the beat goin' ... Don't keep it to yourself!
"If a man does not keep pace with his companions, perhaps it is because he hears a different drummer. Let him step to the music which he hears, however measured or far away." --Henry David Thoreau, "Walden," 1854
"There's a lot to be said for Time Honored tradition and value." --In memory of Frank "fiacovaz" Iacovazzi
"Maybe your drums can be beat, but you can't."--Jack Keck