I was just mentioning that with the marginal amount of cold we have had so far, Ice condition are poor as well as water bars and bogs, So were in a catch 22 for arctic cold we need it but then again we don't as that would hinder snow.
Yes, 12" minimal for a base, And that will depend on the density of the snow, Powder will just hide obstacles so you want to start with something firm and go from there.