I'll have to second or third the recommendation of putting antiperspirant on your feet. Wearing heavy insulated boots & wool socks,even when a moisture wicking pair of socks are used, makes your feet sweat. This sweat/moisture makes your feet cold while on stand and immobile.
Wear a light pair of socks walking to your stand and change into a dry heavier pair on stand. Add hand/foot warmers, boot covers, sleeping bags, etc as stated works to. The bottom line is your feet sweat while walking to the stand and the moisture robs your heat. Get rid of the moisture and your feet will be warmer especially in your case.