Hello and welcome to FF ! A 16 in. tall tank does not have enough height to build what you want with a false bottom. Once you get enough depth in water to have fish and some kind of filtering system (3-6 in.) you would have 10-13 in. left. On top of that you would add 6 in. of egg crate, plastic window netting, ABG soil, and leaf litter. So suddenly you are left with very little of vertical space for the frogs .

An option would be to build a "dam" with a glass pane and aquarium silicone glue. It has to be totally leak free because any water making it's way to dry section will flood the substrate and create a bacteria breeding bog. Then you could use aquarium under gravel filter plates as a short false bottom, with a couple of lift tubes as access tubes for draining excess misting water out. That way you could have at least 10 in. above the dry area.

Even then would not recommend it. IMO 18 in. height enclosure is bare minimum for more terrestrial darts and 24 in. for the arboreal ones. Good luck !