Don't fancy your chances... this isn't a $149 package designed just for slicing! Adding this would at minimum require FS to keep track of settings on a per object basis rather than for the whole print bed, and some rather intricate calculations to try and optimise movement between different objects since they are now at different heights. To software that came with another printer, Pango, has the concept of combined prints, but still won't allow different settings for different objects. You might be able to do this with Simplify3D using processes, but I can't say for sure. Have you noticed a theme here yet?