[pct-l] Media mail?

[Dan Africk]

Has anyone tried mailing resupply items via media mail? I'm preparing to
send all of my food out to California from the east coast, which is of
course very expensive, and media mail has the same size and weight limits
but is less than half the price. I'm not talking about sending each
individual resupply package via media mail, just the big boxes that will go
to the person who will be sending those packages.
Does anyone know if the post office actually checks packages in any way to
see if there really are books in them?