There are many options out there.
What you want to make sure is that the oven comes with a warranty that covers freezing temperatures. For example the FGM ovens come with a 3 years limited warranty and that covers deep freezing temperatures.
I have quite a few bricked dome ovens that have been installed in the Northern part of the North America, including Canada and they haven't had any issues.
During the winter, even when it is freezing, you can fire your oven to 900 F and the bricks can take it without any problem.
For an oven that can cook 2 pizza at time, I would say a diameter of 27" is ok, 32" diameter is good, 36" gives you plenty of space.