Two practical options were suggested:

1. Use an adhesive screen protector and mark the crop lines on that rather than directly on the LCD. This gives you a physical framing guide without risking the camera screen itself.

2. Install Magic Lantern on the Canon 60D. It can display custom safe-area or aspect-ratio masks directly on the LCD, which is a much cleaner solution for video framing. It also adds other video tools such as zebra stripes.

If you want the simplest non-software approach, a marked screen protector is safer than tape on the display. If you want an on-screen guide that looks more professional and is easier to change, Magic Lantern is the better fit—just remember it’s third-party firmware, not officially from Canon.