how hard (or harmful?) would it be to wire in one of those e-cig's with something to slowly push the vapor out 1-2 seconds, then a playfield exhaust fan starting up 2 seconds after to run for 20-30 seconds? I dont doubt it'd require more frequent playfield cleaning. on the other hand the teeny amount of water-oil vapor settling onto a waxed playfield might become very slippery. I wouldnt think the milli-micrograms of moisture, most all of which exhausted quickly, would be enough to affect the wood, switches, electronics etc, pinball machines do create a bit of dry heat.
theres always silica gel dessicant packs that'd try to absorb the moisture before the woodwork could take it in.

it might be done even simpler, something about the size of an LED bulb containing like a nichrome wire and 0.5cc vapor fluid reservoir, if the vapor naturally rises up. I'd still want a playfield exhaust fan happening.