A temperature drop at night to around 72 degrees is needed to induce breeding behavior. While a night-drop isn't necessary outside of breeding season, especially one that low, it wouldn't be harmful either. Considering the basking area can reach the mid 90's, a year round night-drop of 10 degrees isn't out of the question. The actual building of this enclosure is still a year or two away, so plenty of time to make changes
The humidity on the other hand is going to be pretty stable. I am going to shoot for 60% humidity. That will be maintained just by the amount of ventilation and plants in there. Not going to bother with the misters/foggers, the dart frog keepers can have em. For it to support true highlanders a humidity change would be required too, right?
After looking into the Bical's growing habits, that seems like it would be a good fit actually. Some cool pitchers and vigorous growth. How long could that live happily in an enclosure of that size though? Could it be kept indefinitely with careful pruning and potting?
So far the ampullaria seems to be the best plant it and forget it nep for this project. The only drawback I can see is that it prefers to stay wetter than most others? I would hate for the snake to be in competition for floorspace, how quickly do they spread?