[Nomad]

I do this thing all the time. I took some inspection mirrors and brazed a nut on the bottom of the bracket. Going to use them first as a mirror on the inside like usual, but started to use one to reflect light into the repair to cure more quickly and effectively, especially when the sun was a bit low and curing time was beginning to get long.
With the knuckle of the mirror able to bend in any direction it was easy to stand the mirror up on the WS and turn it to aim the light right at the repair. Then I found that curing under pressure, which I do a lot, was helped along by aiming the light from the opposite side that the sun was coming from so that the cure was even on both sides of the injector. I leave it up to cure the pit and it cures hard in, I expect, around half the time. I don't use this all the time but it does come in handy once in a while.
I don't think distance would affect it, but aiming a smaller mirror at a spot a ways away can be difficult sometimes. The knuckle that allows the mirror to swivel in any direction is what makes this work well without a lot of fuss as long as you aren't too far away. Also, use a suction cup that isn't too floppy. I had to switch at first because the cup I was using just couldn't hold the mirror stead enough. I had thought of using more than one cup but haven't tried it yet.