You could get a second hard drive. Pull the first one out, put the second one in, do whatever you want. When/if it's time to return, put the first drive back in. They'll wonder why you've barely used it but whatever.
I did this when laptops were $1500. Now that they are $400 it's usually not worth the bother.
The purchaser would have good reason to zero out the drive before return. That would protect personal data and coincidentally not leak any additional usage info to the supplier.