Nice build so far, humidity levels shouldn't be too much of an issue if you go with riparium plants. But any of the higher humidity plants, i think will suffer some. What is your projected water level?
I assume plans are for the mister being installed in the canopy? If so, go to your local supermarket that has misters for their produce. That is what your result is most likely to end up like.
their set ups are very close to the basic mistking set up.
You mentioned forest floor. Are you talking about the sphagnum used for substrates? That stuff starts to stink and rot if kept overly wet for a period of time, so just be cautious.
Good luck with the build. Should be awesome!!