I did something similar last winter with my Orinoco. I am in zone 9 so when it gets cold it does'nt stay cold for very long. I had a 5' Orinoco last year and I cut open a large tomato cage and put it over the base of the plant upside down. I then filled it up to about 3' with mulch (leaves, pinestraw & wood chips). When it did get cold (like below freezing), which was usually just overnight here, all of the banana leaves would freeze, turn brown and die. I would always cut away the dead leaves from the top of the plant. I was not certain that the plant had even survived but low & behold each time we had a frost a week or so would pass and new growth would start peeking out of the top of the plant.
I cannot promise that this will work for you in zone 7 but based on my experiance, if you keep the base of the plant & corm nice & warm with mulch, it should keep the plant alive.
...Mind you that I have only been growing banana for 2 years and I am certain that there are many more on this forum with much more experience.

Good Luck!

- P.S The very same plant grew another foot this spring/summer and then bloomed & fruited in August.