How can Inkscape open an existing .svg file with pre-selected Inkscape & Document options?

Is there a command line option to specify a template other than the default,
or specify preferences without opening a Dialog?

I've played with the --verb-list and grep'd through hundreds of extensions for the past 6 months,
and haven't found an answer.

I need to set the 'step' value to 56.25, set the document and ruler units to 'cm', and set the border values to 3cm.
If you have concrete examples of setting these values outside of the GUI, that would be appreciated.

If there is no current way to do this, how do I submit a request to add a command-line option to specify document & inkscape prefs
without using the --Dialog options?

- Susan