On a couple of occasions I had to do something similar.  Instead of actually deleting the polygons, I just gave them a material assignment, called "ghost", that had all values set to zero, except for transparency and its falloff were set to 1.  This material doesn't render, but if I ever need to revert, I can just assign the adjacent material to the ghost mat and it will look unchanged.  I first discovered this working with the old conforming clothing that had "caps" in the sleeves and collar that often showed when they shouldn't have.

Not relevant to your question, I know, but rather to what you are trying to accomplish...