Same issue! Years ago, I bought some "heavily" insulated "booty" covers. When I got to my stand, I left my walking boots on. I slipped these insulated booty covers over my walking boots, and put two pocket warmers in each booty, between my walking boot, and the booty cover.

Result, sometimes my feet got so hot, I had to open the booty covers to let a little cool air in! I also wore good sub zero socks, I forget where they came from.

Bottom line, COLD feet make my hunting trips miserable. I HATE cold feet, the above worked. I don't have a clue if the "Booty Covers" are still available. I used them for years, and unless my kids had grabbed them, I stil l have em!