I used to have a mobile home in the mountains. We stayed in it on weekends until the snow came in the fall. The temperatures were well below freezing before we would winterize it late November.
We had "heat tape" on the water inlet hose. and any plumbing outside the home susceptible to the weather. We set the electric furnace thermostat to 60 degrees and never had any freeze problems even with the ambient temperature into the 'teens overnight.
You did not state what kind of heat you have, so you may have to adapt.
I fear, that without proper winterization of your unit, you may be asking for trouble...... even if it is not occupied for only a couple of days a week.