iA Writer fix for large screens

I know iA Writer’s core asset is their lack of features and options. But I really wish the fullscreen experience on my iMac more closely resembled that of my iPad:
• less wasted space given to such huge gutters
• consistent 65 char line length is good
• resulting fewer lines of text would improve focus — recall, focus mode on iPad just 3–5 lines of text

View attachment for side-by-side of feature request.

I’ve been sort of able to “hack” it with system zoom to get rid of margins and make font size big enough for comfortable reading at my standing desk — where viewing distance is about 4 feet from display, hence occasion for 40pt type. But would obviously prefer an option to zoom in-app, preserving resolution and fullscreen active window.

Any other iA Writer users out there with similar ideas? or thoughts on how to approach iA to get this implemented?