Kzinti in Larry Niven's "Known Space" series: After they lost the war, they were punished by being confined to their home star system and only their home star system.
Having the RNZ form a shell around the inner parts of the Romulan home system works well on many levels. It allows for the long-tailed comet,
Having the outposts be about where the orbit
of Mars would be relative to Earth, makes the map shown in Balance of Terror work quite nicely. The neutral zone would just inside of that orbit.
It allows for the long-tailed comet we saw, Scotty's comment about impulse power makes more sense, and the outposts being situated in a solid iron asteroids could indict that the outposts are located in a Romulan's asteroid belt.
With the spread we see, a single ring of the inner Romulan star system would be comprised of approximately 140 outposts.
Of course this map doesn't work for any other episode involving the Romulans.