I had always been told to leave the foot down too, to avoid stressing the spring!
Maybe BEST is to just take the foot off so you can take pressure off the spring and still have no metal contact? But then the foot is probably more likely to get lost...maybe tie it to the presser bar with some thread or something... My "family" of machines is still small enough it all lives indoors in my sewing room, which I keep very comfortable.
I'm trying to limit my machine collection by telling myself I can't keep anything I don't use at least once a year. We'll see how that goes, though...I'm still too attached to everything to let any of it go!