It all depends on how much below freezing it will get.
Firstly, here is a link to get Airstream's winter camping guide:
https://www.airstream.com/community/...inter-camping/
Secondly, a couple of general tips:
The main thing is going to be avoiding your plumbing from freezing and bursting pipes, etc.
Obviously, keep the trailer heated inside. Most coaches route the heating ducts close to the pipes to keep them from freezing. Depending on how cold it gets for how long, you may need some extra propane and/or electric hookups to run a electric heater.
If it's going to get considerably below freezing, disconnect any outdoor hoses.
Alternatively, completely winterize the camper and do not use any water in the coach, and use facilities elsewhere.
Keeping comfortable inside is very doable, avoid contact with the bare walls to avoid the shock of near freezing metal on skin.
Those that have over-wintered in below freezing temps have a wide range of of things they do to skirt the bottom, rent a large propane tank, rely on electric heat and so on, you can search the forum here for ideas.