Have you considered something like this ???
http://www.amazon.com/dp/B002QBNYJU/...SIN=B002QBNYJU
I looked at these about a year ago... if you mount them on a conventional scope, you can adjust them to illuminate the field of view of your existing ( day time ) scope, for any distance you would shoot a rifle...
my understanding, is that they aren't tactikool, as someone off to the side, could see the green beam from rifle to target, but anything you would find in your target, is only going to see the green light...
I've never tried one for night varmints, but would like to...