IF I understand you correctly (Essentially you want a larger viewport with fewer layers visible for context around another viewport at the same scale with more layers for greater detail), I suspect that just placing your second viewport on top of the first would be all you need to do. You can use Ctrl-R to cycle between viewports.
If you're not happy with that, putting a wipeout between the two viewports may help, but check your PDFs/prints, because sometimes wipeouts can be funny (showing up as black rectangles), and display order is always a lot of fun with them!
Another option to look into is viewport clipping (just type CLIP and follow the prompts).
HTH
dJE