Like I said if you so not stand to lose or suffer what's the harm in giving them an additional month?

Additionally, if you really want to find a deal this way you'll need to keep on marketing to these people.

These are professionals with additional training and a stricter code of ethics.

California isn't the problem here.OP will want to consider his IRC Sec 121 exclusion, and all capitalization to basis over the years to mitigate the tax exposure.To everyone suggesting an IRC Sec 1031 exchange: You can't 1031 business rental real estate into a personal residence.... 

These are professionals with additional training and a stricter code of ethics.

In addition, they have always paid my $50 late fee, which compensates me for allowing this behavior temporarily.

Your equity is reducing your possible returns not increasing your cash flow.If your father has no use for additional income he could leave it where it is and not care if it is impacted in a market shift or he could pull it out and invest in a income fund or a REIT. 

The below link takes you to a BP post that provides some additional information on this: https://www.biggerpockets.com/forums/93/topics/493...

I was quoted an additional $70 to have it done.At first glance seems like it's worth having done and if it is detected negotiating it out with the seller.

I will look for a landlord/tenant lawyer to add it to the lease when my tenant gives me the move out date.It's good to hear everyone is have good experiences with Cozy