TWO MODELS?
Now that we are getting into the details, this seems to me like one of the very few cases where it might be best to have two models: a static, purely existing-conditions model in which you would create the "before" renderings, and the regular multi-phased production model where you would create the "after" renderings. Heresy, I know, but better than jumping through all those hoops and compromising the integrity of the production model for the sake of a couple of existing-conditions renderings. (Which, I have to say, in over 30 years of doing this kind of work, I have never once been asked to provide.)
I fully agree that multiple Design Options are a total pain the the butt to deal with when you are working with existing conditions.