The rubber boots are the problem, your feet will sweat and there's nowhere for the sweat to go.
One option I did not see was for rubber bottom, leather upper pac style boots. They're perfect for sitting in a tree stand. My feet start getting cold in the mid/low 40's when not steadily moving and I wear pac boots all the time. The liners transfer the sweat away from your foot and it collects on the outside of the liner. When you take the liners out after taking the boots off, the inside of the boot will be wet, but the inside of the liner and your feet will be dry.
I also sweat in Gore Tex boots, not as bad as a rubber boot, but I still sweat. The boot liners that Raptor posted definitely work though. I have the Ice Breakers, I put them on over my pac boots in extreme cold for stand hunting.
Two pairs of socks just makes your feet sweat. Extra heavyweight socks will also make your feet sweat. A standard mid weight full cushion Darn Tough is heavy enough.
You have two options in the pac boots, ones with an insulated rubber shell, and the other an uninsulated rubber shell. The insulated rubber bottom makes a big difference.
The liner options also make a noticeable difference. The wool felt liners are warmer than the thinsulate liners, especially when your not moving.
I have several different pairs of Hoffman's and Schnee's pac boots. I prefer the 10" height because I don't like the bulk of the taller boots high up my leg.
For the temperatures you are experiencing, you shouldn't need the Schnee's Extreme boots so I would look at the Hoffman's.
Look at either the Double Insulated Guides
https://www.hoffmanboots.com/double-insulated-hoffman-guide
Or the Double insulated Mountaineers.
https://www.hoffmanboots.com/double-insulated-hoffman-mountaineer
The Guides ship with 200 gram thinsulate liners, and you can use 400 gram liners in them if you size them properly. The Mountaineers use the wool felt liners. They are both the same boot with the exception of the liners. The Mountaineers rubber shell is sized to match the thickness of the wool felt liners, but that and the color of the leather are the only difference.
For sitting still, I recommenced the Mountianeers.
Also, if you don't have a forced air boot dryer, get one. Everytime you take your pack boots off, pull the liners out and put the liners and the boot shell both on the dryer. I do this with every pair of boots and shoes when I take them off regardless of the type of boot or shoe.