Hi Kevin,
When I lived up north, I kept fish and water lilies in 32 gal trash barrels on wheels. Winter I could roll them inside (slo-o-o-owly). Summer I could bring them outside.
You could grow your tree in a trash barrel (with drain holes drilled, obvi) and roll it in when temps dip. Or on windy days!
Here's the link to the wheel set. They cost as much as the barrel, but they are so worth it. I have about 8 sets, brought them all with me to florida.
https://www.amazon.com/Rubbermaid-Co...gateway&sr=8-4
Even though I am in florida now, I still grow almost everything in containers. The soil is not so nice (read: sand) and I would waste a lot of fertilizer. I am reading through the threads here on container bananas, to see what I can see. As I understand it, banana roots are only about 18 inches deep anyway, so you can do a lot with a container. Here, nothing outside is on wheels because... hurricanes! Yes, my trees would be sailing down the street. I use the wheels inside only, now.
Oh, the other awesome containers I've gotten are used cattle feed tubs (about 30 gallons, very heavy duty, have a rancher who supplies me) and bright blue 55-gallon food-grade barrels (hundreds of them here from aloe vera juice importers. Imagine.) Cut and drill, perfect.