You're right on the very edge of this fern's cold tolerance, so a combination of warmth from choosing the sunniest aspect, plus overhead cover, will optimize its chances of survival. The car port will confer a significant degree of winter protection from radiational frost if you can move your cooperi under there somehow. But the warmest aspect might still be the south-facing wall, even if that is without overhead cover. Hard up against the house is significantly warmer than even just a few feet away, so bear that in mind. Car port or warmest heat-retaining wall...those are your two best options.

You are so many Sunset zones below the range of that tree fern it really doesnt matter the light exposure in winter. It's the balled and fleeced along with anything else to keep below freezing temps away from the plant that matters. And as you noted they are terrible house plants in winter.
You might be better treating it in winter the way Plumeria(sort of) is treated here-wait until the latest in the year possible to cut off the fronds,wrap trunk in layers of blankets(where it keeps moist but not wet enough to rot),store in dark,frost free area keeping it dormant,uncover in spring..

I agree, this is one plant that seems to hate the great indoors. I have tried this particular species as an indoor plant so many times (and failed) that it's not funny. Even failed in my very humid "Florida" room. I have now had my latest cooperi for about three years now--a record. I grow mine outside from about April through November (letting the pot sit in a saucer of water). Then, I overwinter it in an unheated, frostfree but cold garage from December into mid-March (keeping it on the drier side of moist--if that makes any sense). My biggest surprises--the plant seems to have a better chance overwintering in the cold garage than indoors under warmer (and drier) conditions. Although my fern does not grow actively in the winter, it does hold many of its fronds. It's about four-feet tall now. (Transplanting it as soon as I get this out come to think of it.) PS. I know its not recommended to let the majority of plants sit in water, but I have lost toooo many of these guys to drying out so I try to provide a constant source of water in the growing season.

Basically its how I water some of my plants, from the bottom rather than the top. I then noticed the palm I had was thriving this way(stood on a tray of wet gravel constantly topped up)and my smallr palm likes it too!
I will have to adopt something like this for my Pteris as I just cant keep it green, and its in the bathroom!