First of all, I find that boots made with that much insulation make my feet sweat. you might not notice at first, but it makes your socks damp enough that it can get your feet cold when sitting still. A change of sox is a good idea once you get to your spot. If you will be sitting, another good idea are the down booties. They pack easily, and then you don't need the heavy boots. No matter what you do, it is difficult to keep feet warm when sitting in cold temps for any length of time.