While there is no way to set your own defaults , the PRINT command does offer a lot of ways to modify the settings with a shortcut or custom MENU item.
I personally use a command placed in my custom menu to setup the scale factor, size, paper, and file name for export.
That also allows me to use different commands when printing from the board file or the schematic.
In your case I do not think the PRINT command offers a way to control the margins from the command line.
To see all of the options open up the HELP, navigate to the "Editor Commands -> PRINT" section.
You can then build a command into a shortcut (ASSIGN) and use it to print with your settings every time (other than margins).
For reference here is the command I use when printing from the board.
SCRIPT presets; DISPLAY PDF; PRINT 1 -1 PAPER LETTER FILE %P/../Documents/%N.%E.pdf
First it runs a script with my layer presets (because it gets corrupted internally all the time).
It displays my layer alias for the layers I want printed.
Finally it issues the print command with a max 1 scale factor, limited to 1 page, sets the size to letter, then autofills the location.
Here are my commands used from the schematic (I use 2 regular sizes).
PRINT 2 -1 PAPER letter SHEETS all FILE %P/../Documents/%N.%E.pdf
PRINT 2 -1 PAPER tabloid SHEETS all FILE %P/../Documents/%N.%E.pdf
These do not change the layer visibility since I want everything I normal have visible included in the schematic.
Using these commands also have the added benefit that I do not have to browse to the location every time or have them exported in the same design file location. I have them put into a dedicated documentation folder which is one level up from the design files.
I hope this helps you get something figured out that can streamline the process a little bit using the tools and versions available.
Fyi, whenever I type something in all caps, that is a reference to an Eagle command that can be typed in the command line.
Best Regards,
Cameron
Eagle Library Resources
Kudos are much appreciated if the information I have shared is helpful to you and/or others.
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