I think you would pretty much have to go with some sort of false-bottom type set up. Regardless of how careful you are, water is probably going to end up outside of it's intended place at some point (especially if you put critters in there).
A false bottom allows it to drain out and return to the main reservoir.
I've heard warnings about not putting ultrasonic foggers directly in terrariums if you have critters, apparently some people have reported their critters crawling in/on them and getting injured/killed.
A pretty common thing a lot of people do is find one with a circular opening, and fix some pipe to it, and route the pipe into the terrarium/vivarium/paludarium.
check out dendroboard
, they do a lot of this type of stuff.
And yeah, the carnivorous plant one is quite nice.