I know it sounds a bit "hick-ish" but I get a rock solid rest from a couple of 3-4 ft sticks or dowel rods lashed together with twine about 6-8" one end. Adjustable for height by spreading the legs farther apart, hold the center of the "X" with your off-hand and set the butt of the G2 on my forearm. Next to no cost and if I lose it, no problem.
My 2cents,
Sean