I flatbed printed some multi paneled MDF doors for a company once, where it recesses it gets real blurry, any lower flat areas aren't clean either because the head has to stay at a height to clear the highest points, and just too far away to print clean. Printed reeeaaallll slow the quality was good enough for the customer, but not something I'd want to take credit for doing. You'll get way better quality, and happier customer laying vinyl.