I really feel your frustration on this. It’s kind of mind boggling to me that for all the reptile hobbyists there are in the US, a variety of arboreal cages with dedicated drainage really don’t exist. Dragon Strand cages
are nice, but unless you do a bit of tinkering and drilling, you’ll still have a drainage tray to wet vac every couple of days. The white residue issue (this has happened to my Reptibreeze as well) may very well continue to persist in a Dragon Strand hybrid with a screened front.
Not only am I looking to upgrade my current cham’s cage, I’ll need another cage entirely (and soon) for a second chameleon. I’ve got the same set of requirements you do, for the most part - front and side panels that won’t corrode, and a secure drainage system that won’t leak. I’m considering the following options:
Tamura Designs - I personally keep coming back to these. They’re pricey, but I recently got a quote for custom cage built with all the same features these ones have (plant stands, plant hanging ledges on either side, centered drains in the bottom of the cage, cabinet stands to conceal buckets/foggers/etc. One 2 x 2 x 4 enclosure can be ordered directly from the site. If you’re interested in a 4 x 2 x 4, you‘d have to reach out to the site owner, Dale Tamura for a freight shipping quote (which can get pretty pricey.. And Dale, from what I understand, has been very busy. He can be difficult to get in contact with). The 2 x 2 x 4’s will probably run you about $200 in shipping, but they ship flat.
Zen Habitats - I‘m sure you’ve seen these before! What I like about them is that you can order a 2 x 2 x 4, or TWO 2 x 2 x 4’s without having to ask them to split a 4 x 2 x 4 in half (if you’ll be keeping more than one chameleon). Obvious downsides here are that you again would have to do your own drilling/tinkering to get branch ledges and drainage set up. My fiancé can get aluminum channel easily and on the cheap from his job, but depending on your circumstances, making your own aluminum ledges may require a trip to the hardware store. If it’s helpful, I had considered installing
these drains in the bottoms of my Zen Habitats (should I go that route), but they’d need to be sealed with water proof/aquarium silicone to be sure they don’t leak. The edges of the cage bottoms would likely need to be sealed as well, which would make disassembling the cages without ripping the interior walls up almost impossible (assuming you would ever need to disassemble the cage). I saw
@Klyde O'Scope mention that it may be possible to email Zen Habitats and ask for a bottom screen instead of a solid bottom panel. Zen Habitats does offer free shipping!
Last but not least..
I actually reached out to
Toad Ranch recently. Very nice, responsive bunch. They make a beautiful product for terrestrial reptiles. They are actually who I got my custom cage quote from. I think for anyone planning on keeping a chameleon in a Toad Ranch cage, you would need to make several tweaks to the base cage (and some of those tweaks aren‘t features they normally offer, like drainage). Long story short, they will work with you on a custom build, but what I personally needed ended up being very pricey. What really drove up the overall cost was shipping (they ship via freight). I’d love to go with these guys, but not sure that it will be feasible in the end. Just something to consider if you think about reaching out!
. I keep coming back k to Tamura designs and trying to get ahold of Dale the past week+ (makes sense you say he's really busy). I've specifically been looking at the 4x2x4 also but was scared to even think what shipping would be 
I’m in CA. For me, two 2 x 2 x 4 enclosures WITH shipping and sales tax came out to $1716.39. Shipping was $208.34, sales tax was $153.22. I had it all calculated in the checkout, I just haven’t pulled the trigger yet. Give it a shot, that way you’ll know exactly how bad it will or will not be 
