This won’t help for your proxy problem, however:
For 1,000,000 passengers to drop 3000 pounds of weight, each passenger must lose (3000/1000000) = 0.003 lbs per person. That could be achieved through jettisoning every ones shirt, or shoes, or probably even fingernail clippings, saving everyone. This assumes efficient collection and jettison before the weight loss needed increased as the plane used more fuel.
Actually, they don’t allow fingernail clippers on board anymore, so that’s out.