These would be plans for the architectural review committee, so accuracy of scale is very important. I am not changing sheet sizes at all. They are still D size. I was hoping for a simple setting in preferences, but I do not see any. Currently my work flow goes like this to achieve the scale change. After I set it up once, my other project went really fast - about 10 minutes.
Draw a line from a point on the reference model, for insertion of the paper space items once re-scaled.
Set the reference model to 1/8" = 1'-0"
Left to right highlight all paper space items (including the line drawn in 1 above) and upscale by 2.5 (1"=20' up to 1/8" = 1'-0") The example I show is incorrect scale at 1" = 10'
While the paper space items are highlighted, group them.
Reset the insertion point of the highlighted group to the end point of the line drawn in 1 above.
Shift highlighted group to point on the reference model where the line from 1 above originated prior to scaling.
General clean-up