This is exactly my plan for my custom build! At first I was thinking what size I should make it that would fit the dragon ledges, but then I was like why dont I just make my own dragon ledges??I would modify that one and include horizontal pieces in the frame work to hook on your branches... Kinda like a wood dragon ledge.
I would do a smaller diameter so it is easier to zip tie branches to them. Do the first one about 7-8 inches down for basking. Then where ever you want for latch points. If you add a few to the back panel you can utilize more of the cage space as well.
Sorry not good with building specifics but I can see it in my head. lol