If memory serves me correct, I believe that the shaking camera syndrome usually starts at about 15,000km from the center of the map with a really noticable difference over that range, say 18,000km. With proper planning, you shouldn't have a problem filling objects, planets, nebulas, asteroids, etc into a 30,000km diameter along all three axis x,y,z of a map. Although 30,000km may not seem like a lot of room to work with, you'd be surprised how much one could fit in that area. At normal intercept speeds, it will take a decent amount of time traveling 15,000 - 30,000km in-game. The only problem would probably be load time of a map that is truely decked out.