couple of thoughts:
in some cases, especially with lots of separate elements in the file, putting a uniquely-colored box around the entire design and just setting it to ignore in the GFUI can help.
you may have items/errors in the file that render fine in a preview, but that the GF struggles with. If you feel like uploading your file, someone here can inspect it.
If you have a CC version of illustrator and a mobile device, downloading the free Adobe Capture app might help you skip the whole scanner thing.
there are tutorials in the Matrix that could help you out, but not knowing your skill level with photoshop/illustrator I’m not sure which specific tutorials I would recommend… maybe this one?
or