This year I'm overwintering all the bananas with barrels that have their bottom cut out. The steps are.
1. Cut off all the excess foliage which can't survive the winter anyways
2. Shrink wrap all the trunks
3. Add additional insulation if necessary
4. Stick a cut open plastic barrel over the entire banana stem
5. Fill the barrel with leaves
6. Add additional leaf bags with leaves if the stem is too long
7. Shrink wrap the entire set up to keep it stable
Here's the musa mekong giant which was much easier to over-winter since it is still very small.