Here's a shot of the 6" and 3" roof playing well on my TLX version of some Dragonshire parts.
And here are the pieces resting comfortably on the desk. I will apply some real textures to them now, and I'll make the pieces without the overhangs, too.
One thing I realized was that the flaps I had created at the top to overlap one another and cover up any gap works well when they're tucked into the truss. By folding them inward, they press up against each other and make the build look even cleaner.
Next step is to make up a template for a middle truss, on the assumption that two end trusses back-to-back won't be pleasing enough. Then the angled pieces, which should be interesting.