Strijkbout: I haven't played I-War in a while, but for I-War 2 you have to be within 5km to target subsystems.
Or use the zoom once it's installed. That extends it out to 25 or 30 km, don't remember which. This also makes it handy to mark cargo pods for Jafs without having to fly within the shorter 5 km range. Er, I-War2, that is.
I agree with your tactics for mines. Just use the manual override to fly backward at a similar rate, so they never close the distance to your ship. In I-War2 I think at the first mine mission you have Lori and Az in the turret fighters, so I sometimes just set them to fire at will and they do most of the work. The downside is that they burn through all of their missiles on stupid mines, when it's not really necessary. To avoid that go back to the first tactic of backing away and picking them off, without using the girls.