Re: Feeding sugar from the bag, over inner cover, as some do with fondant...
Did some experimenting feeding on the upper side of an inner cover. Have a 2 1/2 inch feeder rim. The center hole in my inner covers is 3 1/2 inch in diameter.
Placed 4 inch squares of block candy around the perimeter of the center hole. Cluster would move up through the hole and work on the blocks some 75% of the time. In cold weather, the bees were down below.
Had 2 inch insulation on three sides of hive and then black paper aound. Thinking of adding 3/4 inch on front side this winter. Bought a $7 thermometer c/w humidty meter and placed it beside the blocks for my curiousity.
The notch in the inner cover was down and open and also had a 3/4 inch round hole in front side of feeder rim.
This configuration has minimal impact on hive temp and good for curious bee keeper.
If you always do what you always did, you'll always get what you always got!