You know, this whole thread is a good reminder than any cham can be quite individual in personality despite some commonly-reported species traits (Ousties are mellow). Not always! I know this doesn't really ease the tension for YOU though! Sorry!
Too bad he just seems to be a stressy, needy guy. A good thing is, he's got some reserves so isn't starving. I know you've been adjusting his setup to try reducing stress. He might be a cham who just does better without a cage entirely. I had a melleri like that. She never tolerated even a very large cage, she seemed too preoccupied to eat much, and I was worried to death about her. I finally set up a free range clump of fake and real Ficus in the corner of a room with a climbing route as high as possible, put the feeders in a hanging deeper plastic box where she could watch them as long as she wished and sneak down to hunt without being in plain view, and she became a different girl. Once she realized she wasn't as confined she settled down and ate like a pig, was very approachable and almost friendly. Just an idea.
I don't like giving conflicting advice as I know how worried you are. But, IMHO, putting him by a window so he can see trees and bushes that he can't get to might preoccupy or frustrate him even more, especially if he's WC which I'd suspect given his behavior.