Z-fighting is a technical limitation you have to work with. CS 1.9 gives you some more flexibility as you can control the perspective matrix with it manually (and hence choose a matrix with a more limited depth range, but better 'separation' at distance) but fundamentally the problem won't go away.
Thanks for that info - yesterday I made an internal coordinate rescaler to deal with that problem, and it worked (at least with the distant positions that are currently used - currently rescales at a 5:1 ratio, the 1 being a single GL coordinate unit). One issue I've noticed with high ratios is that the frustum culling seems to go crazy - I tried finding a way to change/rescale the view frustum, but couldn't find anything. I'm attaching a pic showing what things look like at a 100:1 ratio (everything near the camera is clipped).