Recently purchased a 2017 Winnebago 31BE. How long could I expect my propane tank to last under these conditions; slide pulled in, small electric heater running, temp, 29 to 40, out in the open, heat...
I guess that is why you often see RV's wintering with a big bottle of propane connected outside. Your current usage seem to indicate about 7-8 days under those conditions.
I would certainly go up to the max with electric heaters instead of the propane furnace, but do watch if it gets colder that your tanks and valves are protected.
I like pipe tape around sensitive spots that comes on when the built in thermostat calls for hear.