I saw a discussion recently on the Vectorworks community board where a Vectorworks user was trying to get an outline of the property onto the site model.
There is a way to copy the property line and have it appear on the site model, and have it follow the contours. In simple terms you need to convert a copy of the property line into a 3D polygon.
There are a few steps that can make this very easy, and I have covered those in the movie.There is some great protected information here that is only available to paying subscribers. You must be an active paying subscriber to see it, but you can Subscribe here.