Live plants serve several purposes in themselves (cover, leaf surfaces to drink from, moderate humidity) but they don't necessarily have to support the cham's weight all the time. Keepers often use biovine, artificial plants, or sturdier naturally barked branches threaded through the foliage but anchored to the cage frame or screen to provide travel paths. A larger bushy Schefflera can support an adult cham on the thicker stems. I also prefer using Ficus alli instead of benjamina. It is a bit less tempermental and much stronger. One of many reasons my cages are larger than most keepers' is that I can use the bigger plants that are more robust.
You'd be surprised. Ficus and hibiscus are probably your two best. But umbrella plants do very well as well. My gang isn't particularly large, but they hold up very well in the umbrella plants.
well if you are looking for good free range plant pick up a hibiscus tree, i was into gardening before chams and i have loads of hibiscus trees in my yard and they love them, and there durable enough to hold any cham.