We do the same with 2 electric heaters, one in the front and one just before the bedroom. WE turn the furnace way down at night, we sleep cold, then in the morning I will make the coffee and turn the heaters and furnace up a bit for breakfast and shower time. By running this way the furnace only runs once a day for ten minutes or so, the Elec heaters keep it warm from then on. Am looking for one of the very small 400watt heaters for the wet bay to keep the frost off in the real cold times. By keeping the temp up and the windows and vents cracked we stay quite dry. Another thing at night we shut all the vents and windows(no added moisture other than our breathing) plus put the covered foam vent cushins in and you would be surprised how much difference by using them makes.
LEN