Updating this, in case it helps anyone else who shares this particular OCD about consistent line strength. After a little measuring and a lot of trial and error, I determined that the native resolution of the new writing area on the Note Pro is 1320x1761 pixels. Any image file with those dimensions will show up without distortion while the toolbars are open.
Obviously if you minimize the toolbars to use “full screen” mode, that is no longer the case - but unfortunately we can’t have it both ways. Imho this is a small price to pay for the vastly improved toolbar that no longer blocks part of the file itself.
Attached are a few templates I made for my own use. I prefer tighter line spacing and finer lines than the default templates provide; if you have a particular design and can’t figure out how to make it yourself (the humble MS Paint is quite good for this), feel free to make a suggestion and I’ll draw it up for you.