I have always felt a bit sorry for the Galciv miners. It's a tough and dangerous job blowing up asteroids in zero gravity and zero atmosphere then collecting all the bits. They get very little thanks. And to make it worse, in the event of war who gets zapped by every passing ship? Yup, the poor defenseless miners.
It's time they fought back. They are grisly, determined, tough and armed with all sorts of dangerous gear. Send a second, or third mining ship to the same asteroid field and it should be reinforced - not such easy pickings. By the time you get to the 5th reinforcement level they should be positively dangerous.
I am pretty sure it would not be difficult to introduce different levels of asteroid mining. It could even become part of defensive decision-making. Suppose level 5 mines actually attacked enemy ships that came within 1 hex?
Now that would be a fine thing and a fitting tribute to those frontier pioneers and a surprise to the alien invading scum.