Do the clamps mount to existing factory holes or do I need to drill?

These mount at factory points — no drilling required. Test-fit the cover once it arrives to confirm clamp engagement before tightening permanently.

Can I leave this folded down while driving, or does it need to be fully latched?

The cover is designed to be fully secured while in use. If you plan to run with it partially folded for airflow, verify that the exposed sections stay stable at highway speeds before relying on that setup.

What's the return window if this doesn't fit right?

Contact ModSupply directly with photos of the fit issue — they'll walk you through options before any return is processed.