You won't have to re-do the boning. If you only delete entire groups from the figure mesh, then morphs on the remaining body parts will still work. Save your reduced mesh under a different name, take a copy of the figure's CR2, and edit it to point to the new mesh. As an alternative, there are reduced resolution versions of V3 and M3, currently only available for DAZ|Studio; but shortly to be released for Poser as well.