On second thought, I did a slight test by setting the rope thickness to a ridiculous value and have discovered that the thickness has NO relation to the drawing distance.The main issue is to convince different ships to use a different rigging.ini file that has a different rope thickness.
That might be possible in a "Different Flags" mod kind of way, but is not simple to code at all.
So even if we COULD have the thickness depend on the ship size, it'll make no difference at a distance.