Submitting L visa app via friend

I live in a state that does not have a Chinese Embassy so I would have to submit my papers through the SF Consulate since it's in charge of the state I live in. Travelling there to submit documents in person is not financially enticing, as is using a visa agency. I was wondering if anyone has ever mailed their passport and documents to a friend/family member they had living locally in SF, and had them submit the application on your behalf with a successful result? Using the mail would be way cheaper than a visa agency if it works out.