Hi...i live in New York area, i put a bunch of 2 gallon potted raspberries, and other stuff in my shed over winter....right now i got some serious buds and green growing already, went below Zero couple nights this winter........every variety of every type of plant has their own resistance to cold, i'm sure if u ask enuff questions here you'll get ur answers

I would move them under the carport so they don't get too wet while dormant. Keep them moist though, do not let them get bone dry. I keep stuff in the garage in pots. Works well!

In zone 7B, it is unlikely that a generously sized container - like one suited to growing a dwarf fruit tree - would freeze in winter. And if you use a high quality potting soil, drainage shouldn't be an issue so they should be able to remain outdoors, exposed to the elements, without worry.

I grow a lot of trees in containers, some much more sensitive to cold temps than most fruits, without worry. The only ones I've lost (and it hasn't been many) have been through my own negligence/lack of care, not winter issues.

There are concerns with growing trees in containers but that is more to do with the correct type of potting medium, fertilizing and repotting/root pruning than cold issues with such a mild zone. The Container Gardening forum has a great thread on growing trees in containers - you might want to seek that out for additional info.