A similar thread for this topic recently appeared over on PL.
As much as you creativity & ingenuity are recognized you need to do some very important research into the processes of creating "fog".
If you use any of the commercially available fluids for creating the effect there are serious side effects from even slightly changing the conditions for creating the "fog".
Any of the glycol based fluids break down into extremely nasty substances that will cause serious damage to your respiratory system if they are overheated by just a few degrees when creating your "fog" !
This is why most machines have that problem of cooling down when used. It's not that they couldn't be hotter and keep boiling off the fluid when applied, its that if it is too hot when you start the fluid is broken down into harmful substances that shouldn't be inhaled/breathed-in by anybody.
Check out the dangers carefully before you continue, please. I have a destroyed respiratory system (from auto painting) and I wouldn't want anyone else to have to suffer through what I deal with on a regular basis.