How do you plan to keep the water left in the lines from freezing?
Garages with Hellcats in them rarely get below freezing.
Undercoat the car. I've used vegetable oil mixed with mystery oil for years. My father in law undercoated his 1986 Blazer every year since new, washed it regularly, and when he got rid of it in 2002 it was because the transmission took a dump - the body was 100% solid. Same can be said for his 90's Cherokee...
I've drilled holes in doors, door sills, door jambs, trunk lids, sprayed behind taillights, headlights, behind wheel wells... wherever I could get it. You spend 1 good day preparing the car with holes and plugs and then doing it every summer/fall only takes about an hour. I see rotted Chargers and Challengers every day in Buffalo... When you see a paint bubble, it's already too late. 1 day of your time and $5 in materials is well worth the investment.
I'm a subscriber at the local car wash place (Delta Sonic) and I see the carwash several times per week - but I'm pretty sure they recycle the water, so I'm getting blasted with saltwater every time I go through... it's moreso to get the white powdery salt off of the car to keep it off of my clothes.