Yeah I have used the same setup that I have now with a five foot hose and it has always worked fine. The heater also has a sensor that will cut it off if there is too much CO2 in the air.
Yes the tent is very cramped and on a slope! Most of my gear is in the other big tent though and it is the one that I am worried about collapsing as soon as it snows here.
Maybe you can let it down on top of your things before it snows and cover it with plastic or a tarp. That might keep it from ripping.
That is not a bad idea. The condensation would be awful in that scenario but it might be better than losing the tent.