OP are you familiar with annotation objects? It should be easy as 1-2-3. You are correct that you draw 1:1 in model space. It is your viewport in paper space (layout tab) that you set your zoom scale at (don't forget to lock it after).
Are you used to dimensioning in model space? Or do you dimension in paper space?
If you hit the F1 key and read up and practice creating annotation text and annotation dimensions, then you should be able to dimension on the fly at your desired visual scale. A related command would be CANNOSCALE, which tells model space what visual scale to display annotation objects at (there's a distinction between model space being 1:1 and having the visual scale set to match the anticipated viewport scale you'd like to have in paper space. You want 1/4" = 1'-0" in paper space? Then set the visual scale to 1/4"=1'-0" in model space. That doesn't change the fact that you draw at full scale (1:1) in model space.
If by some odd chance my nattering was useful -- that's great, glad to help. But if it actually solved your issue, then please mark my solution as accepted 🙂