Also you can try a setting little higher than what you are using now and see. I like to load late, the hottest part of the burn takes care the temperature drop through the night and when it gets to the stage of the burn that you mentioned, is day time. Enough to keep everything warm as long the temperature climb a little or the sun is out.Probably. It's just (as probably everybody here experiences) that at that point (room starts to cool off) there's so much coal left that even with vigorous compression (aka hitting it with a shovel) there's hardly room for half a load.
So I guess I'll program my smarthome to send me a text "Living Room temperature too low, time to swoosh up a bit" when that happens ;-)
Or put a stepper motor on the thermostat...
When I am off in AM I turn the dial up to enjoy my coffee.