I used to work for a smaller firm where we did have to do this. This was before Export Layout was available. What I would do is to use Chspace to move the VP and TB to Model Space. Then I'd use EXtrim to trim out everything outside of the Viewport. After that I would WBlock what was left to a new file, undo and start the next layout. That was the best we could work out at the time.
I tried that last week. However I found it changed object sizes, annotative text scales, resized and repositioned object labels. It was not pretty at all. Maybe I had something set up wrong? So much to learn.
Kindest Regards Michael, Draftsperson (Exploration Technologist) Civil 3D 2013 Windows 8 Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz 32. GB 64-bit Oepration System, x64-based processor No Pen or Touch Input