I did at one point try pushing the near plane away for Step 1.0 (and bringing in the far plane) but I found that even as near as 1.0 was still too far. I'll look at it again.
If I recall correctly, you were able to use w buffering in Direct3D, which sadly is not something that's possible to force OpenGL to use (though some implementations of GL might do just that). For now, I think I just divide all the coordinates by 1024.0 at the very end or something like that.
I'll have to hook up some more Step 1.0 games. I thought we had Sega Bass Fishing working under GL back in 2004 flawlessly, however...