Those are all great plants that are cham-safe and look good in a bioactive enclosure, as well!
I would use at least 1.5 inches. It’s hard to tell what will work best for you as everyone uses different amounts of water for misting/maintaining humidity. As long as you have a way of removing excess water, the drainage layer can be modified to suit your need. Unfortunately, using bioactive substrate requires a little trial and error. My thought has always been that more soil means more plants and roots. The more plants you have, the more water they will absorb. So if you mist very heavily, you may need to drain your substrate much more often when you first plant, as opposed to a year down the road when the plant life has properly filled in.
Misting, and misting heavily is recommended to allow the chameleon to properly clean their eyes. I personally get around this by using an outdoor enclosure during part of the year. I can leave the hose running forever and it wouldn’t hurt anything. In an indoor enclosure, periodic misting sessions of 5-10 minutes (a couple times a week or so), can, and most likely will stretch a drainage layer to its limits. This will be very problematic early, when your plants are still young. I don’t ever have an issue with humidity either, but we aren’t misting to solely maintain humidity.Well maintaining humidity is not a problem, I live in a humid area so the enclosure won't be heavily misted. I also intend to have 9 inches of substrate in a 2x2 feet area and lots of plants.
Make a feeding cup/jug/pipe with drainage in the bottom. Put the bowl in the least misted part of the cage. Full Throttle Feeders sells a PVC pipe feeder with drainage that works well. I made my own version that works just as well, too.I have a question. I have an exo terra feeder dish, with regular misting, the water will get into the dish and possibly soak the calcium dust and drown the feeder insects. Any solution to this?