Thanks, Miles. It looks like a great community!
So I'm still curious about all of this but I have an idea that may work for the roof. I'm still wondering if anchoring it the way I described before would work. If not, I'm thinking about building a heavy, metal-framed roof and welding it to support poles that run down into the ground. I would then build the earthbag structure around those poles. That seems like it may be overkill but I want to make sure this is permanent. Cost might be a major factor with that idea though. Any other ideas?