First why the hang up on LIGHT? The rifle is no feather weight in the truest sense or what's 3-4 oz one way or another and that's about all even heavy ones weight.
But about the lightest combination I know of is Weaver two piece base and Tasco Aluminum rings. If you put them on and leave them and don't ever take them off the Tasco rings work pretty well. They are not for taking on and off tho. I use them once and toss them. Or I shoud say I did. No longer use them. Now I use Burris Signature rings almost always.