I have similar system 300W solar w/ 300 AH of AGM batteries. I run the furnace at 60-64 degrees (my furnace draws less than 4 amps when running). All LED, and all electronics are modern and efficient. No battery usage for heating water, cooking etc-all propane for that.
Usually 12.5 ish when I get up (and nothing's on). Usually up to the 14.4 volt regulation point by 11 or 12 AM.
A few days of cloudy cold weather could throw this for a loop-with the furnace running 24 hrs and little recharge-but there is the generator. In general my off grid trips are a week or less and if there is a deficit, the solar can handle it later.