I forgot that the fire sits directly on the pan and surrounded by the Cone.

You'll need 22 g aluminumn (.02563" @ .357#/sqft). Anything thinner and I'd be afraid of burnng through it.

How about three tabs of windscreen material riveted to the Cone. The tab, with a hole in it, would fold out from the Cone. Push a stake through the tab and the aluminum sheet to anchor it to the snow. Not only will the Cone tend to slide on the aluminum sheet but there will be a layer of ice that will form under the aluminum sheet making it want to slide around on the snow / ice. You may even want to put a couple of branches under the aluminum sheet to space it off the snow.