You are correct, commercial growers take the bananas when they are green. And you will have to do the same. If you take them now, you will be taking all peeling. The plants leaves needs the sun for energy. So the leaves will need to be open when warmer weather rolls through.
Your plant will plump the bananas up. This is a long process. What makes it longer is the fact the weather makes your plant shut down, go dormant...as in normal physical functions being suspended or slowed down for a period of time; in or as if in a deep sleep. And watching bananas plump up is worst than watching paint dry.
You are right, freezing bananas will destroy the trunk, leaves, and fruit.
If (and this is from a banana addict) we get a repeat weather snap like last year here in Florida, I plan on purchasing a greenhouse or making one around my DCs. During the nights when temps drop below 40, I will keep grow lights on and maybe throw in a small electric heater.
Now, worst case, you can attempt to xplant to a very large pot and move the plants into the garage and keep it warm with lights. Doubt you would want a fruiting banana tree on your carpet as they drip a nectar that's harsh to cotton materials.
TGirl - how many plants do you have?
Something like this may help your plants too:
greenhouse items - Get great deals on Home Garden, Books items on eBay.com!
Most are less than $100 on ebay. Just make sure there is no floor. Now you can build a greenhouse around your plant and not shock it by digging it up.