New layers and old viewports

I work in drawings that sometimes have upward of 100 layout tabs (a
contract requirement). These viewports are set up at 1" = 100' for
utilities mapping. One drawing may cover several miles with
information specific to each viewport set on layers created
specifically for that viewport. This is done so as to not allow
information in adjacent viewports to be seen in the current one. The
viewports are often turned at various angles as they follow the given
route of the C/L and trhus the text is angled differently in each
viewport.

My question is how do I add new layers in model space and keep them
from showing up in the existing viewports in those layout tabs? I
recently had to add some new info and create a set of new layers. I
then had to go to each layout tab which contains 1 or 2 viewports and
freeze the new layers. How can I avoid this? The information is placed
into the drawing in a coordinate system, so placing it somwhere else
in model space is not an option.

Any help will be appreciated.