See if using Arch objects works for you. I was able to produce an ortho with the Arch Objects included, and the files are much smaller.
The files were indeed smaller (33 mb for ACIS versus 10 mb for ACAD Arch objects). The problem is that my resultant dwg is all messed up (see pictures attached).
The first is the ACIS (which is what i see in Revit) and the second is the ACAD Objects (messed up).
Any ideas on what's causing this?
I'm using both AutoCAD Plant 3D and Revit Arc/Str/MEP 2012 versions.
PS: Both work fine when creating an Ortho View