Whatever you do, don't move the light so far back that it will illuminate your pins from the archer side. The stray light will not only hit the pins but everything else on your sight. This will effectively cause anything beyond the sight to appear totally black (Same principle as the cop putting the light in your eyes when he approaches you.....just not as extreme)
I would opt for one of those smalll battery powered blue or violet lights like this one
Velcro it on your riser shining at the pins. They work great.
If you want a higher end solution, the Pro Light DX by LP archery works great. I have one and for hogs the thing just can't be beat.
Pro Light DX