crazy banana

I would not touch the pup for several reasons. 20" is pretty short and may not have sufficient roots of its own yet. If left until spring, it can nicely develop into a strong pup with a good corm and root system. Second, if you think that the mother plant is very close to an inflorescence, why stressing it by removing a pup?
A dwarf plant with a p-stem height of only 5.5' can easily be wrapped in frost cloth. I use Agribon which comes in different thicknesses. You should be able to overwinter and save the mother plant with the potential fruit bunch and all the pups.