You're doing somehing different than what I proposed.  Let me do it in steps to try to be more clear:
- Under the live view, click the placement button and choose "Template/centered"
 - Add your image(s) at your 594 x 420 size with crop OFF
 
Now when you are in Template/centered 
placement mode which is a special placement mode, your crop marks will be on the red outline(s) and not the print itself.
P.S.  This has nothing to do with layouts or the [Template] thumbnail.  Here you are using the Template/centered placement method.
Regards,
Mike