Good morning, sorry you have been waiting so long for a reply.
If the car is not going to be driven and is just going to get snowed on my suggestion would be to use an ONR wash at 256/1 when possible to wash the vehicle. When it gets to be below freezing there is not much you will be able to do other than wait for the temps to get above freezing to wash the vehicle. So my suggestion would be as follows-
Wash vehicle with ONR at standard dilution
The colder it gets the more that Instant Detailer seems to work easier than Hyper Seal. Hyper Seal will still work its just Instant Detailer seems to dry better.
When it is freezing I would hold off on any detailing. The ONR will just freeze to the surface.
When it gets warmer out and you are going to be driving it I would recommend doing a paint decontamination wash with Power Clean and Ferrex and top with Hyper Seal.