Sounds like you plan on keeping them outside all winter?
I have no experience in your climate zone but I have spent some time in 8b. One thing I have done with good results during the shoulder seasons with tender plants is to keep them, along with 5 gallon black plastic buckets/lids filled with water, in the sunniest location possible during the day. At night I sandwich the plants against the building with the 5 gallon buckets (which have warmed up very nicely during the day) and place a blanket or some other convenient form of insulation, row covers work fine, over the buckets, plants and or/pots depending on plant height. The water in the buckets of course is slow to release its heat and as it does it keeps the plants warm.
I haven't tried this through the winter in my area because it is so often overcast and rainy that I have just assumed it won't work, and I have been fortunate enough to have a nice garage to use for overwintering.
I must say though, I have experienced very overcast days while the buckets were outside and was surprised at how much solar energy they were able to absorb.
I suppose you could heat the water every day, but that might get pricey. Or take your showers at night and bring the buckets into the shower with you.....
