While active camouflage might help...it's still fucking huge. It's larger than a football field. Longer than the stadium, for sure. I'd say, that if the Hindenburg disaster didn't happen, or if there were already fast maneuverable flying things(for example, dragons. And the fact that they breathe fire might make people think a bit sooner about "Hmmm. Maybe our flying ships shouldn't be explosively flammable, when there are flying things that breathe fire." thus meaning no disaster, or at least a much smaller one. So I'm thinking airships(not your size, but still) would be in use. Especially with dragons; unmanned surveillance balloon doesn't even have to come down for maintenance. Thus, anti-airship missiles might exist, if not widespread use and development.
Also, remember that when you're that big, and 'surprisingly light', wind and weather will affect you more. They did for airships in general, and when you get that high(apart from obvious pressurization and air issues, still don't really think you can get to 200,000 feet at all, considering 140,000 or so was the max for most airships' and bad for them, too. Speed is still a bit much, IMO), winds will be a factor. Far more so when landing, depending on region. 20000 to 60000 is where winds get really high.
Now I have to look up aero graphite...
When I was doing my research, I found that the pressure, complexity, vulnerability, and a slightly different pressure issue were the main issues with walkers. Which is why my only 'legged tank' is going to have ten legs. And another four that are also arms. Others are going to be relatively small. The centurion, for example, will only be about 4 and a half meters tall, and a mere 13 tons. It's going to link directly into the persons brain and motor cortex and the like so that they can control it by 'moving', and get tactile sense which corresponds to different conditions in it's status. As to the sword, I can see where you're going, but there are supposed to be two magnetic field generatorsin the center which create a venn diagram like shape where they overlap, and in the middle is where the plasma goes. Though your idea is good, and I like it for turning it off, I don't know how you could get the centrifugal force.
As for bunkers, nuclear bunkers would surely need to be big enough to house dragons, but artillery bunkers or normal ones? Not so much, when they can fly. Though, burrowing dragons present a risk, and that, to me, would just mean they'd be deeper, harder to make, as they might be made through stone or harsher/harder soil that dragons have an difficult or impossible task of getting through. Which means, to me, that bunker busters would be something like tandem charges; bomb is dropped, bomb fires a shaped charge into where it's going to land, which is also a bunker buster, blows a hole, big one goes into that hole, penetrates even deeper, and then blows up.
I'm going to present the specs n the Centurion in a little bit, once I do a bit more research and I cna make a post without it being a wall of text.