Those are pretty much your options.
Though, I’m not sure that the motion file is what you need to accomplish your goal.
The motion file only contains stepper and laser commands. While you can use that to generate images that show the contents, there really isn’t any easy way to manipulate them.
And, if you did, there is currently no way to import those changes back into the GFUI to use them.
Did you ever give this a try? This might be a better path. You should be able to re-import the SVG into the GFUI. That would solve your exact scaling issue, at least.